[1] The village is situated approximately 6 kilometers from the border with Costa Rica, at the Raudal del Diablo rapids of the San Juan River.

The site on which the village of El Castillo is built was initially established in 1673 as a Spanish fortification to defend against pirate attacks upon the city of Granada (which can be reached by navigating upstream from the Caribbean Sea along the San Juan River into Lake Nicaragua).

The most notable of these was in 1670 by the pirate Gallardino, who approached the city from Lake Nicaragua after navigating up the treacherous San Juan River from the Caribbean Sea.

On the morning of July 26, 1762, a combined British and Miskito force laid siege to the fortress in what would later be called the Battle for the Río San Juan de Nicaragua.

[5] In 1781, King Charles III of Spain issued a royal decree granting Rafaela Herrera a pension for life, as a reward for her heroic defense during that battle.

[8] After Spain entered the American Revolutionary War in 1779, Major General John Dalling, the British governor and commander-in-chief of Jamaica, proposed a second naval expedition to Nicaragua.

The goal was to sail up the San Juan River to Lake Nicaragua and capture the town of Granada, which would effectively cut Spanish America in half as well as provide potential access to the Pacific Ocean.

This makes a daytrip a practical option for visiting the reserve; one can hire a guide and arrange river transportation in El Castillo.

The only significant health care facility is the Venta Social de Medicamentos Inmaculada Concepción, a pharmacy located in the center of the village, south of the docks and nearly halfway up Loma Nelson.