Travel in developing countries

Travel in low-income countries can be challenging to people used to the higher-income world. Infrastructure for transport, electricity, water, communication and money transfer might be deficient, and there may be problems with food safety, health care, and sanitation. Poverty might induce begging, scams and crime. In some places corruption is also a problem.

Prepare

“

I have a neighbor who knows 200 types of wine.... I only know two types of wine – red and white.
But my neighbor only knows two types of countries – industrialized and developing. And I know 200.

”

—Hans Rosling, Professor of International Health

Money

Main article: Money

The concern regarding exchange rates and that (hard) cash is the preferred and sometimes only option of payment is especially true for developing countries. In some less-developed countries, the local currency may be so weak or so inflated that foreign currency (such as U.S. dollars) is used in larger transactions.

Many poor countries are high-fraud areas; don't be surprised if an attempt to use a payment card, make a VoIP call or access a password-protected website which always worked fine in your own country suddenly gets flagged as suspicious by your home providers just because you tried to get access while travelling. Countries with widespread poverty, weak enforcement of criminal laws or ongoing corruption attract all manner of fraud. Contact your card issuers and the operators of any service you intend to rely upon while abroad, so that they know that you are travelling and can tell you if certain countries are blocked due to fraud and abuse. Carry a non-toll-free number for your bank or credit card company. 1-800 and similar "toll free" numbers are typically valid only in a specific home country: they won't be useful in a developing country if you need to resolve a problem with blocked funds or to report a lost or stolen card.

Electricity

Main article: Electrical systems

Research the voltage and plug configuration before travelling with plug-in devices. It is rather frustrating to arrive and find that your most expensive item, some piece of electronics, cannot be recharged or used. "Universal" adapters with plugs for every conceivable outlet on earth are handy, but they tend to be heavy and expensive so if you know where you're going they're overkill – and adapters are not enough when voltage or frequency do not match your device.

Developing countries tend to have power failures more often than high income places. While Germany on the one hand has 15 minutes of power outage per year, some less developed places may have at least an hour without electricity per week. Also when there is power, there may be brownouts (lower voltage) and power spikes. Don't count on electricity "just working", bring patience and a flashlight. In some places, power is even switched on only for certain periods of time; check before you go, and in such locations, consider accommodation with their own generator or solar panels (usually equipped with batteries for the night but don't count on it), if available.

The quality of power supply can vary widely within a country. While an outage of a few hours in the capital may make headlines, more rural dwellers can only laugh as they read the ridiculously capital-centric newspaper's coverage by candlelight, themselves having such outages daily.

For some places, it would be a fine idea to get a surge protector to keep your electronics safe from voltage fluctuations. In most places, experienced travelers simply don't rely on electronics and wisely leave them at home, knowing that carrying expensive devices only paints a target on their backs for pickpockets or petty street thieves.

Vaccines and medications

See also: Medication

Many countries will deny entry without proof of appropriate vaccinations. In particular, a number of Central and Western African countries and French Guiana require all incoming tourists to be vaccinated with yellow fever vaccination. Refer to Yellow fever for more information.

Ideally, visit a travel clinic at least two months before departure to plan any vaccinations or prescriptions you may need (see Stay healthy below for more info). These doctors specialize in travel medicine and can give you advice that is more specific to your travels than a generalist physician, who will likely know little more about local conditions than what's on their national health websites. Still, any doctor is better than none.

See our article on the COVID-19 pandemic for general information about vaccination requirements for that disease, and consult the governments of destination countries for specifics.

Travel insurance

Main article: Travel insurance

Although travel insurance should be purchased regardless of where you travel, it is especially important when travelling to developing countries, especially since the cost of dealing with emergencies can add up quickly, In particular, since medical facilities in developing countries are often not up to the standards of more developed ones, you can likely get a better standard of care by being evacuated home, or at the very least to a more developed country by air. As medical evacuation flights are very costly, you should definitely ensure that your travel insurance policy covers this.

Get in

Visas

Main article: Visa

The availability of visas ranges from "no visa needed" or "visa on arrival for (almost) all high-income countries" to "tourists are a nuisance to our glorious leader". While much has improved since the fall of the Soviet Union, there are still corners of the world where letters of invitation are needed or an arm and a leg are charged just for the application and visas are routinely denied for no other reason than "We don't like your face" (which is how third-world citizens are often treated in the western world). Some developing countries may also be in different stages of conflict with other countries in the region or developed countries far away, resulting in visa trouble.

IATA (the International Air Transport Association) provides a database which is usually up to date and is the way most airlines judge whether you need a visa prior to boarding. If you lack a visa the database says you need, you will be denied boarding. You cannot directly access that database, but IATA have a travel information web page which covers vaccination requirements and customs rules as well as visas.

Many airlines and some travel agents can also provide visa information, often based on the IATA database. Sites such as Project Visa or Visa Hunter also have databases of visa information for each country. However - mostly for legal reasons - none of these sources including IATA provide any guarantee for their information, so double checking with the embassy or embassies in question is a good idea if there is any doubt.

Not all overland or river border crossings are open or intended for citizens of third countries (i.e. a crossing between two countries may be able to handle citizens of those countries, but not citizens of any other country) and even those that are may not routinely provide visas on arrival, which may make your trip needlessly complicated. If you can, find out in advance what's the case and ask multiple sources. Try to get the answer in writing from as official a source as you can, which not only ensures smooth travel but will reduce the risk of being asked for a bribe.

There are two schools of thought for getting visas: one says to obtain visas as far in advance if possible, so you can buffer for unexpected delays, while the other says to obtain as close to your destination as possible, where you can get your visa rapidly and with less hassle as it's a more standard procedure. Ideally you can combine them by starting your trip at a "visa hub" city where you can get visas for nearly all neighboring countries (but some countries insist you get the visa at some specific place, depending on your home country). Some examples by region include:

Eastern Europe and Central Asia: Kyiv (Ukraine)
South-East Asia: Bangkok (Thailand) and Singapore
Southern Africa: Pretoria and Cape Town, (South Africa)
Latin America and the Caribbean: Houston, Los Angeles, Miami and Washington DC in the United States; and Ottawa in Canada.

You can also obtain visas for almost any country in the world in Washington D.C., Tokyo, Beijing, Moscow and Western European capitals including London, Brussels, Berlin and Paris. You can also mail your visa application and passport to the nearest embassy or consulate (use registered mail). However, applications done this way tend to be time-consuming and expensive.

Mental preparation

See also: Culture shock

If traveling in a developing country for the first time – or in a new part of the world – don't underestimate the potential culture shock. Many a stable, capable traveler has been overcome by the newness of developing world travel, where many little cultural adjustments can add up quickly. Especially in your initial days, consider splurging on Western-style and -quality hotels, food, and services to help acclimatize.

It may help to think in terms of "rupees" and "whoopies". The terms originated with a two-year-old who could not pronounce rupees, and called them "whoopies". The parents decided that their travel budget included some of each, and that the distinction was important. When the tourist restaurant has an expensive lunch and you walk down the street to a cafe full of locals and eat basically the same meal for a third the price, you are saving rupees. Good move. However, when it is hot, noisy, dusty, and there are beggars everywhere, and you take refuge in an air-conditioned restaurant even though it serves bad lamb-burgers for twice the cost of the tourist restaurant's lunch, you are spending whoopies. Enjoy the cool and don't worry much about the cost.

Often a good escape is the buffet breakfast or lunch at a good hotel. Many of these are very good and some superb. These are generally outrageously priced by local standards, but often quite reasonable by Western standards.

Immigration troubles

See also: Corruption and bribery

If you are arriving at an international border, immigration officials may actively solicit bribes, particularly preying on tourists from richer countries. Southeast Asian countries like Cambodia, Indonesia and Vietnam are such hot-spots. Use of violence against tourists who refuse to pay for bribe is not unheard of.

The following advice may be useful:

Make sure that you are aware of legitimate charges that border crossing entails (either at exit or entry) and get a receipt for them if possible.
Make sure you bring all required documents when crossing the border, as it is a common pretext for immigration officials to claim that there are problems with your documents before they solicit a bribe.
Consider using major border crossings (such as the capital's airport) instead of small border crossings.
Avoid entering at night, as sleepy tourists are better prey of corrupt officials, and fewer people passing through means fewer witnesses.
If the officials insist for a bribe:
- Pretend that you cannot understand their request, as some officials may soon realize that it is too time-consuming.
- Arguing with the officials based on law is largely futile, and may probably provoke the officials. Threatening to lodge a complaint to your country's diplomatic missions may make the situation better or worse depending on the circumstances.
- If you are brought to another separate room, be prepared that the officials may be at best preparing for a protracted war, and at worst, preparing for physical violence. Observe the officials, and prepare for the fact that you may be forced to pay a bribe.
If possible, memorize the name and/or staff number of the official, as it helps filing complaint to your country's diplomatic missions and/or local anti-corruption agencies.
Lastly, if you are not demanded a bribe, don't try to actively bribe the officials. Not only may your act encourage further corruption and cause more trouble to future tourists, but you may also commit an offense in both your country and the destination — most countries have laws to prosecute those who are involved in corruption regardless of territorial jurisdiction.

Arrival

Some of the following is also advisable in some high income countries, but is often doubly valid in developing countries.

In many places any obvious tourist or newcomer will be swamped with offers of guides, hotels, and taxi services. It's important to look like you know what you're doing, and not be forced into accepting an offer just because you arrived unprepared.

In many places, it is better to avoid the people yelling "taxi?" inside the airport or train station; they are often touting for or driving unlicensed meter-less taxis. Furthermore, they often make their money by taking you to specific hotels, which give them a referral fee. You are better off taking the airport bus or going outside and looking for a real taxi with a license and often a meter. In some countries (Peru, Mexico, Colombia, etc) the real licensed taxis are only allowed to wait within a certain taxi rank, with a ticket seller or dispatcher there or inside the terminal building. You buy a ticket from the dispatcher or ticket seller and then hand the ticket to the driver at the taxi rank. If there is safe reliable public transit, it's often worth it to familiarize yourself with it and avoid the taxi altogether.

One way to avoid the crush, especially in India, is to use a local agent for booking accommodation or internal travel in advance. When you arrive at your destination the local agent will be waiting with your name on a notice and they will have a driver to take you to your hotel. It might cost a little bit more but it beats walking out of an air terminal at midnight after a long flight, into pandemonium.

A good arrival checklist for these situations includes all the tips for Arriving in a new city plus:

A plan. Know what you're going to do before you arrive. No matter how much you want to get off the stuffy bus or out of the crowded airport, you don't want to find yourself pondering your guidebook in the middle of a crowd of touts and hawkers. Everyone will insist on taking you to this guest-house or that hotel. Looking like you already have a goal and a plan (even if you don't) is your first line of defense against the rain of business cards and brochures. If traveling with friends, a good strategy is to leave the luggage with part of the group at a nearby restaurant or cafe while the other half gathers information on what's available. This gives everyone the excuse 'we are waiting for our friends' and will relieve some of the pressure. If you are traveling alone, just insist that you are meeting a friend who already has a room for both of you. As a last resort, don't hesitate to just ignore any especially insistent 'guides' or 'friends'. They will leave you alone, eventually. Sometimes just briskly walking through the crowd like you know where you are going, will do the trick. That is of course especially helpful if you do.
Knowledge of costs. Have some idea of what a taxi into town should cost (in the local currency), and enough language (or a piece of paper and pen) to negotiate it. Expect to be charged more than the locals, but at least this way you should get the right number of 0's. If arriving by plane, just ask someone on the flight. And of course, always negotiate the price ahead of time, before entering the vehicle.
Knowledge of alternatives While some developing countries don't have much public transport to speak of and taking it is usually not advisable for all but the most daring travellers, there are other places (especially big cities) with remarkably good public transport, especially to/from the main airport and/or bus or train station connecting to the city center respectively. Some public transport systems are a bit complicated or require a card or coupons for payment. Familiarize yourself with the local quirks and get a map of the system as soon as possible (they are sometimes available online, but even a city as big as Managua has none whatsoever). Be sure to have an idea of the situation on the ground before heading out. If public transport isn't an option or you just prefer a cab, familiarize yourself with the look of official cabs and modes of payment. Sometimes an airport taxi has to be paid with a voucher that you can only buy in the airport, sometimes there are "city" and "airport" taxis, both legal official and safe but only the airport taxis allowed into the immediate airport area and thus much more expensive. In general "unofficial" taxis are best avoided and you should have at least a general idea what a legitimate taxi looks like. (e.g. license in the windshield, a specific color, the word "taxi" on the roof or a variety of other markers)

Get a local data SIM card

See also: Mobile phones

Many low-income countries "skipped" landline telephones, but readily embraced mobile phones, meaning mobile networks are often surprisingly reliable. When traveling in a developing country, get at least one local SIM card with data allowance. In most cases, this should be the first task after arrival. Almost all international airports have options available. Websites like the Prepaid Data SIM Card Wiki have an abundance of information for almost all countries. Sometimes it is less hassle (and also reduces the chance of theft) to just buy a cheap "burner" phone with a pre-existing SIM card built-in.

Always having access to the internet is a vital tool for comfort and safety. You can communicate your location and information in seconds, have map and translation access, and a huge amount of information from other travelers which came before you. Wikivoyage is the best example. If you find yourself in need of urgent help, an internet connection or an emergency broadcast message from a local mobile operator might make a difference.

If you or one of your travel partners want to omit mobile internet out of conviction, think twice if this is a good idea. You can always turn off mobile data, if you desire "to be free from all that technical stuff" or make your phone battery last longer. Make sure to download an offline map of the region for navigation, because internet connections in some locations can be very spotty and unreliable.

Get around

Infrastructure in developing countries is generally not up to the standards of more developed countries. Visitors should plan more time to cover the same distance. Safety can also be an issue, particularly if air or sea travel is involved. Rail travel might be slower than buses or entirely unavailable if a network built in the colonial era was not properly maintained or updated since then.

Some remote inland locations may only be feasibly reachable by boat or air travel (possibly bush planes), with a corresponding increase in cost, hassle and time to get there.

Do some research before you go.

While sometimes the government subsidizes surface (and even air) transport, lack of competition can drive prices significantly.

Why is the one-hour hop on a Cessna $200 one-way? Perhaps the alternative is an old bus that takes at least 24 hours and may or may not break down on the dirt roads that get you there. In places like Cuba there are essentially two travel networks, one for people with hard currency and one for those without. While the former is often outrageously priced by local standards, the price may be reasonable to a western wallet if the perks (air conditioning, faster travel speeds, newer vehicles) are worth the extra cost.

On the other hand, you will most likely interact less with locals and get less of a feel for what living in one of these countries is actually like.

In some cities, such as Ho Chi Minh City, there are large and well-known taxi companies which are generally reliable, and with drivers that are more likely to be honest; it is worth doing some research to find out what those companies are, and to only take taxis from those companies when you are there. Other cities, such as Bangkok or Beijing, may not have those large taxi companies, but you can minimise your risk of getting scammed by avoiding the taxis parked outside hotels or tourist attractions, and instead flagging down a taxi cruising down the street, or catching one at a taxi stand used mainly by locals.

In some parts of the world - especially the post-Soviet world - shared taxis provide a (relatively) safe and efficient means to get between cities for a reasonable cost. These aren't really "taxis" so much as they are private vehicles that wait until the car is full before embarking on their journey, but they will often drop you off right at the doors to your destination. A general rule is if the locals are using it, it's safe enough for you. Some drivers will (try to) charge you as a foreigner a slightly higher price; most will quote you the same cost as they're charging other people in the car. They may also offer you a higher price (usually 4x the low price) for the full car. This is preferred by some travellers as you don't have to wait for people to fill the car up (which may take upwards of hours depending on your destination) and you don't have to share the vehicle with strangers. Shared taxis will queue in specific parking lots, usually near bus or train stations, and drivers will yell out their destinations and costs.

The major downsides to shared taxis are their unregulated nature and the need to have a relatively strong command of the local or colonial language in order to bargain with the drivers. But in some places, like extremely mountainous Tajikistan, shared taxis are the way to get between cities.

Talk

See also: Phrasebooks, Talk

Try acquiring some knowledge of the local language. Yes, you can probably get by on just English in most of the world, but even the ability to say "hello", "please", "thank you", "excuse me", and so on in the local language goes a long way. "Leave me alone" and "don't touch me" aren't far behind. Numbers, "how much does it cost," and "too expensive" are also quite useful.

In several countries, especially in former British or American colonies, you can often get by with just English. For example in India or the Philippines, nearly every educated person speaks some English and many are fluent. Even many of the less educated have some English, at least recognize some simple words and phrases. In such situations, it is possible to travel using simple English – basic words and phrases. The key is to use just such common words and phrases, and learn to pronounce them in a more local (or locally comprehensible) accent.

For long trips in a region, consider learning a regional language if there is one. For example, Russian is widely used in Central Asia where many countries were once part of the Soviet Union. It is easier to learn a bit of Russian than to tackle all the local languages — Tajik, Uzbek, Turkmen, Kazakh, Kyrgyz — and may be almost as useful. French plays a similar role for parts of Africa, Spanish and/or Portuguese in Latin America. For very basic communication a pidgin of Spanish and Portuguese is often understood by native speakers of both languages if you speak slow enough and use simple, clearly enunciated sentences. Your chances are better when using Spanish with Portuguese-speakers than the other way round. For English speakers Russian, French or Spanish may be easier to learn than the local languages.

All other things being equal, the age of a person (young adults often speak foreign languages better than old people), the urban or rural character of a destination and its general economic situation are good predictors of foreign language proficiency. For example, many young people in Costa Rica speak some English, whereas only a small subsection of the urban youth does in Western Nicaragua, a much poorer region.

Sleep

Do not sleep on a mattress or pad on the ground in areas where you do not know the local fauna. If you are going to camp out, bring a camp cot or hammock to keep you away from snakes, scorpions and such. Use mosquito nets around your bed in countries where mosquitoes carry malaria, dengue or yellow fever.

In some countries there is more or less explicitly a distinction between hotels aimed at locals and hotels aimed at foreigners. While sometimes the distinction is mostly price, location and the ability of staff to speak English, in some cases you really should avoid the hotels aimed at locals, especially if they rent rooms by the hour.

Stay safe

If you are from the developed world, your income is likely enormous in relation to that of many people in some developing countries. The UN estimates that nearly a billion people live on under US$2 a day. If you wander into their territory waving around a camera whose price exceeds local annual income, expect a reaction. Even your backpack, boots, watch and clothes may each cost a few months' local income. If you insist on using these items, consider altering them to (1) make them look dirty or rusted, and (2) reduce their potential resale value. Do you still have your old worn-down backpack around? Can you use a cheap secondary phone for routine needs and leave your more expensive smartphone for when you really need it?

In addition, ethnic stereotypes and perceptions may affect how locals view you. For example, Chinese travellers may be stereotyped as wealthy businesspersons who habitually deposit and use large sums of cash, which makes Chinese more prone to burglary and corrupt officials.

Reactions vary, but be prepared to deal with:

aggressive sales tactics and being charged more than locals, see Bargaining;
police and other government officers requesting bribes, see Authority trouble and Corruption and bribery;
various scams aimed at tourists, see Common scams;
thieves, see Pickpockets;
beggars, including children being exploited by adults as street beggars, see Begging;
violent crimes, such as armed robbery and snatch theft, particularly in big cities like Caracas, Johannesburg and São Paulo.

Take precautions, but do not get paranoid about it. Of course some people want your money, but don't let that spoil a trip.

In parts of Asia and Latin America, aggressive dogs are another concern.

If travelling in a country that is experiencing widespread violence, such as a civil war, you need to take many extra precautions, see War zone safety.

Police

For more information on how to cope with corrupt officers, see the Corruption and bribery article.

One unfortunate fact of life is that police corruption is likely to be more of an issue the less developed a country is. As such, you should not expect much help from the police if you have been a victim of crime, as criminals often bribe police officers to avoid arrest. You should still make a police report as the police report would generally be required for you to make an insurance claim on the value of any items stolen.

It is also not uncommon for police officers in developing countries to ask for bribes, especially with regards to traffic offenses, crossing borders, problems with documents and the like.

Stay healthy

See also: Water, Medication, Travellers' diarrhea, Infectious diseases, Sunburn and sun protection, Altitude sickness

Developing countries pose health hazards. Many have poor sanitation, poor health care and a hot climate that allows various diseases practically unknown in temperate Western countries to propagate. Quite a few have stray or feral dogs and cats, and some have exceptional numbers of rats, which may spread diseases.

Many countries have immunization requirements for certain diseases (such as yellow fever). See a doctor with experience in travel medicine, or visit a specialist clinic, at least 8 weeks before your planned departure. This gives enough time for the vaccinations. It is also a good idea to ensure you do not have any major ailments before travelling, as access to good medical care in the event of an emergency is often limited in developing countries.

Hepatitis is common in many developing countries and can be spread through contaminated water. Effective vaccines are available for Hepatitis A and B, but not for Hepatitis C. Consult with your travel medicine specialist about whether you should get these vaccines.

Although rabies is endemic in many developing countries and feral dogs may increase the risk, rabies vaccines are awkward, usually unnecessary, and should only be considered if you are going to do things that heighten your risk (such as working with animals). If you think you want the vaccine, talk to a professional with an understanding of your situation.

Malaria remains a problem in many developing countries. Malaria existed in Europe until at least World War II; mosquitoes may carry malaria even in cold climates. Also yellow fever and dengue are carried by mosquitoes. The malaria mosquitoes are active mostly at night, those that carry dengue mostly in the day. Generally the best prevention against mosquito transmitted diseases is not to get bitten by mosquitoes in the first place. Covered skin will be bitten less often, so wear long trousers and long-sleeve shirts or pullovers if you can. Mosquito nets are an effective and cheap way to protect yourself at night.

AIDS and other sexually transmitted diseases are poorly controlled in many developing countries. If there is any chance you will have sex with anyone except a long-term partner, carry condoms.

Contaminated drinking water is one of the leading sources of health problems for travelers. Check country listings for your destinations for details of hazards there, and for availability of bottled water or alternatives. Consider carrying a means of purifying water, portable filters are useful and inexpensive. A good filter takes out everything down to 0.2 micron, all bacteria and many viruses. Boiling or ultraviolet (UV) radiation may be even more effective, depending on what you want to get rid of, but those require equipment (like a stove) that you might not have in your lodging. Iodine tablets are widely used. Consult a doctor with knowledge of the area you are visiting.

Inorganic water contaminants, such as insecticides or heavy metals, are a different problem and cannot be dealt with by the usual sterilization methods. Check our destination articles and government health warnings to see if these will be an acute problem – usually the health effects are from long-term exposure.

Carry a diarrhea medicine; you are almost certain to need it at some point. Loperamide is an inexpensive and effective generic, available in most of the world. For many destinations, sun screen and mosquito repellent are also essential. Carrying your own anti-bacterial soap and hand wipes can be a useful precaution. For some journeys, a full first aid kit is advisable.

Your diet will change somewhat to suit unfamiliar foods and you may lose nutrients due to various illnesses. Using one-a-day multivitamin tablets is a sensible precaution. To greatly reduce your risk of food-related problems remember this rule for fruits and vegetables: peel it, wash it, boil it or reject it (though be careful, too, about the safety of any water used to wash a vegetable).

Cope

Packing

See also: Luggage, Packing list

For travel in developing countries, you may need to carry things you would not need nearer home:

A sarong is useful as a sheet, beach blanket, towel, and of course, sarong wrap.
A luggage lock: expedition shops and airports sell these. Or if backpacking, consider a 3D flexible lock that wraps around your entire pack.
Money belt or passport pouch for your valuables. See pickpockets for more detail.
A little flashlight designed to hang on a keychain
Guidebook, phrasebook or Wikivoyage printouts (and a memory stick with the pages you did not print): these can be very helpful, and the more unfamiliar your destination is, the more useful they are. Don't count on finding consistent Internet access once you arrive.
Map: often these can be bought cheaply in the destination country, but you should bring your own for countries such as China where you cannot expect to read the locally-printed map.
Toilet paper: keep a roll or wad of paper in your luggage and a good wad in an easily accessible spot. Public toilets and guest-house toilets will often not provide any. If you're short on space, remove the cardboard tube and flatten the roll. Keeping it in a large zip-lock bag is another good idea.
Food: trail mix, granola bars or other sports snacks travel well. They can be very handy when airport food is ridiculously expensive, when nothing nearby looks sanitary, or when everything is closed for two days because of some festival or strike.
Medication, including personal supplies of medications that you are taking

Budget travellers will also need:

A sleep sheet (sheet sewn into a bag): the cheaper hostels do not provide bedding .
A towel: Hotels and hostels may not provide one, or not clean ones. In cold weather areas, drying off quickly is much more important than on a tropical island. Making room in your pack for a good towel can keep you healthy and happy. Bath and beauty shops sell small super-absorbent towels for drying hair, but they work just as well for general use, and dry quicker than regular cotton. To save space, go with the smallest size you're comfortable with.
A padlock: some hotels don't have door locks, but give you a padlock with which to close the door of your room. People who work at the hotel almost certainly have duplicate keys for that lock. Using your own lock is more secure.
A rubber doorstop: works wonders if you don't have a padlock.
A universal rubber plug, for use in sinks and tubs where no plug is provided.
A clothesline

You might also need:

Sewing kit
duct tape (to save space, consider wrapping a few feet around a large marker or Sharpie, instead of bringing a whole roll)
pocket knife (only in checked baggage of course)
lighter or a waterproof container with matches (plastic photographic film boxes are perfect) (most airport restrictions prohibit the carrying of matches onboard)