Exclusion zones

An exclusion zone is established by a sanctioning body to prohibit specific activities in a specific geographic area for control of populations for safety, crowd control, or military purposes; these differ from other next-to-impossible destinations in that a government is explicitly prohibiting visitors instead of simply providing no infrastructure.

Environmental disasters

In Japan

Namie (浪江町), Futaba (双葉町) and Ōkuma (大熊町) in Fukushima (prefecture)

In Montserrat

Soufrière Hills Volcano Exclusion Zone. The capital was built at the base of a volcano that was dormant for hundreds of years. That changed in the 1990s, and the southern half of the island had to be evacuated.

In Ukraine

Pripyat (Chernobyl)

Military

War zones tend to be dangerous or impassible for travel; there are also exclusion zones around a few key or remote military bases.

Military bases

In Australia

Pine Gap is a top secret signals intelligence facility for the U.S. and Australian militaries, and is therefore closed to the public.

In the United States of America

Area 51, a US Air Force base which tests prototype war planes, is legendary for a high level of military secrecy and therefore accepts no visitors.

Demilitarised zones

Various demilitarised zones have been established as areas of reduced military presence on the border between two states in the aftermath of armed conflict.

The Korean demilitarised zone is best known; a similar zone once existed on the North-South Vietnam border.

Entire ghost towns have been created by military conflict; in rare cases these are abandoned as military exclusion zones:

Varosha (near Famagusta, Cyprus) has been abandoned since the 1974 Turkish occupation of Northern Cyprus and heavily-armed Turkish soldiers prevent visitors from entering or taking photographs of the crumbling seaside resort town. It has been declared reopened by the Turkish military on 9 October 2020.

Closed cities

During the Soviet Union tens of cities were designated as closed cities, which in practice meant that you would need an authorization to enter them and they weren't marked on any non-classified maps. These cities were sites of sensitive industry and research and they were often quite large (hundreds of thousands of inhabitants). Some of those cities, like Ozyorsk and Seversk, are still closed. However, some of these cities were opened up after the fall of the Soviet Union, examples being Sillamäe in Estonia and Maylısuu in Kyrgyzstan. Some closed cities are still officially closed, but may now be visited by foreigners on guided tours, such as Baikonur in Kazakhstan, and Star City and Norilsk in Russia. Another example of an abandoned closed city you can visit on a guided tour is Pripyat, the site of the Chernobyl disaster.

There were also secret cities in the Manhattan Project era, entire populated places secretly constructed in remote or desert locations to serve the war effort. Oak Ridge (Tennessee) and Los Alamos (New Mexico) were among these planned communities.

Local or political restrictions

Border zones

In Cold War Europe, a 5 km (3.1 mi) exclusion zone applied to much of the East German (GDR) side of the Iron Curtain; access was strictly regulated, so a few German villages historically within this zone were demolished or became ghost towns.
Similar to the situation of the Iron Curtain, Hong Kong also maintains a border zone known as the Frontier Closed Area along the Chinese-Hong Kong border, which traces its history back to early Cold-War era. The closed area has been drastically reduced after the handover, but still covers some major border townships.
A Border Security Zone still exists at many points in Russia, mostly on external borders where economic activity and access are restricted under the Frontier Regime Regulations of the FSB (Federal Security Service). Foreign tourists need a permit from the local FSB department to visit the zone.
A border zone a few kilometers wide is also enforced on the Finnish side of the Finnish-Russian border. It is marked, but fenced only at some stretches. Entry without permit is prohibited and results in arrest and prosecution. Activities like photography and hunting are prohibited. The area is largely uninhabited, but not entirely; there are some farms right at the border, and even foreigners can apply and get a permit to enter the zone.

Conservation

There are still a few isolated human settlements which contain uncontacted peoples or native groups which do not wish to have contact with outsiders. For instance, it is illegal to visit North Sentinel Island in the Andaman and Nicobar Islands in order to protect the indigenous Sentinelese tribe.
Some wildlife sanctuaries are closed to the casual visitor and provide only a very limited, regulated access under strict oversight to scientific researchers, to protect migratory birds or other fauna or flora, or to keep a pristine area for the research. In others restricting roads to select areas is enough to keep visitor numbers in sensitive areas low enough for wildlife protection.
Some exclusion zones become good sanctuaries for wildlife themselves, despite being established for other reasons. The Korean DMZ is one of such examples, where endangered animals like the Asiatic black bear can be found there. This phenomenon is sometimes called "accidental park" and there are sometimes efforts to preserve the wilderness even after the exclusion zone is no longer needed.

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