El Castillo de la Imaculada Concepcion, located on the San Juan river of Nicaragua, was built in the 1670s to protect Lake Nicaragua and its ports, mainly Granada. Construction began shortly after the pirate Gallardino attacked the port of Granada. The local heroine is Rafaela Herrera, the recently deceased fortress commandant's daughter, that directed the defence that repelled an English invading fleet in 1762. In 1780, a young Horatio Nelson (yes, that Nelson) tried to conquer the fort and initially succeeded but had to leave after 7 months due to almost all of his soldiers (probably including himself) getting yellow fever (not a concern in this area any more). Shortly thereafter the Spanish took the empty fort back.
Since 1995, the fortress has been on a "tentative list" of important Nicaraguan cultural sites with the United Nations Educational, Scientific and Cultural Organization (UNESCO) as a preliminary to nomination for consideration as a World Heritage Site.
You can get in from San Carlos at the south-east corner of the Lago Nicaragua (also known as Cocibolca) by boat (C$75 pp = US$4).
Boats leave San Carlos at 6:30 am, 8 am, 10:30 (high season), 12:30, 2:30 and 4:30. For the first boat, book the day before, as it might be full already if you are too late. You can buy tickets at the muelle municipal half a block from the market, which also serves as San Carlos' bus terminal.
From San Juan del Norte the boat to San Carlos (once weekly 6 or 12 hours, depending on type of service and season) also passes El Castillo and stops upon request.
- 1 Indio Maiz national park (Reserva Biológica Indio Maíz). This national park covers a large region ranging from just beyond El Castillo to San Juan del Norte (aka San Juan de Nicaragua) and northwards. Typically it is visited either in a day trip from El Castillo, or by staying at the Refugio Bartola on the edge of the park. There are plentiful guides providing such trips from El Castillo and the Refugio, who will provide you with the requisite rubber boots. Visitors will see verdant and varied rain forest vegetation, and are very likely to also see various types of monkey, leaf cutter ants, poison dart frogs, and plentiful bird life, with other wildlife sightings possible. In March/April 2018 there were significant fires in the region to which the government responded slowly and rejected Costa Rican aid, causing protests which were soon overshadowed by protests against a social security reform which left to several dead and the ongoing (as of July 2018) civil conflict in the country. It is not fully clear how much of the reserve is still biologically intact or what caused the conflagration.
- Rapids of the Rio San Juan (called raudales) that made El Castillo a strategic place to build a fortress. Raudal del Toro (across from Boca de Sábalo), Raudal del Castillo (across from the fortress) and Raudal del Diablo are the most popular.
- Just a few kilometers downriver from El Castillo you can see Costa Rica on the Rio San Juan's right or southern bank; (the river itself in a political oddity belongs to Nicaragua entirely). They are constructing a new road right next to the river which has been controversial because of its (very visible) impact on the environment.
- 2 Fortress (From the main road, head upwards (away from the river) and follow the signs). The fortress is crumbling a bit, but it offers great views of the river and the rapids that made this place a strategic location for a fortress in the first place Admission US$2, camera permit US$1.
Reading a book in the library which is right inside the castillo. Listen to the sounds of the village and the water running down the river while reading a good book.
You can rent kayaks for various lengths of time or also do a guided tour on kayak. Some adventurous travellers have done the whole trip from here to the Caribbean at San Juan de Nicaragua (San Juan del Norte) in just over a week. Ask whether you can return your kayaks there or not.
There is not that much to buy in town and nothing that you couldn't get in San Carlos. If you plan on spending some time here remember that as of March 2012 there is no ATM in town.
River shrimp (Camarones del Rio) are very popular and quite cheap. However, they are not available year-round, as the government protects them (usually from February to April).
- Casa de Huésped – Restaurante Chinandegano, De la Iglesia Católica 190 metros al sureste, ☎ . doubles as a guesthouse
- Restaurante Ranchón Las Vegas de San Juan, Frente al Puesto Militar del Castillo, ☎ .
- Restaurante Daryzu, Frente al Minisúper San Antonio, ☎ .
Drink the natural fruit drinks at Border's Coffee. The owner (a Nicaraguan) is very proud to say that they are made without water or sugar, and they are very delicious.
Several Hotels in the area are actually somewhere along the river or in the town of Sabalos close by. Some have their own pier. If you know where you are going to stay in advance just tell the captain of the boat and (s)he will drop you off right at the doorstep.
- Montecristo River Lodge, Frente Isla Sombrero de Cuero (Boca de Sabalos, El Castillo, Rio San Juan), ☎ . Check-in: anytime, check-out: anytime. All inclusive: Room, all meals, use of horses, canoes, kayak, trails, fishing gear. US$75.
- [dead link] Hotel Victoria, Iglesia Católica, 200 metros al Suroeste, ☎ , e-mail: firstname.lastname@example.org. single US$35 double US$60.
- Posada del Río, De la Iglesia Católica 250 metros al sureste, ☎ , e-mail: email@example.com. US$20 incl. breakfast.
- San Juan Del Norte
- There are various small villages along the river some of them having hotels and some hotels just between villages. The biggest of those villages is Boca de Sabalos named for a fish that is common around that place.
- El Castillo is a convenient starting point for all your jungle adventures in the reserva Indio Maiz and downriver