Rio San Juan is a department of Nicaragua. It was established in 1957 as territory of Chontales and Zelaya. Its area is 7,473 km ² and has a population of 107,545 inhabitants . Its capital is San Carlos. The department also includes the archipelago of Solentiname and San Juan River, which takes its name. The river proved to be a great connection for the Province of Nicaragua with the rest of the Spanish territory. Through it, Granada and other colonies traded with cities such as Havana, Cartagena and Portobelo. This was known by the pirates who roamed the Caribbean, and soon made inroads through San Juan.