Río San Juan

San Carlos is the capital of Nicaragua's Río San Juan department, sitting at the southeastern end of Lake Nicaragua where the lake drains into the Río San Juan and forms a watery border with Costa Rica. This compact port town works as the regional gateway for boats to the Solentiname Islands, El Castillo and the Indio-Maíz Biological Reserve.

The town's identity is shaped by water, with ferries and cargo boats lining the docks and the malecón looking out over Lake Cocibolca. History runs strongly nearby, especially at El Castillo, where the Spanish built the Fortress of the Immaculate Conception in the late 1600s to defend the river against pirate raids.

The Solentiname Archipelago, a short boat ride away, is known for its artist community, painted balsa-wood crafts and forested islands. Downriver, El Castillo and the Indio-Maíz reserve offer rainforest trails, birdwatching and wildlife such as monkeys, caimans and river turtles.

San Carlos functions as the department's commercial and administrative centre, with markets, banks, small hotels and restaurants serving river fish, gallo pinto and tropical fruit. Its economy mixes agriculture, fishing, trade and a growing eco-tourism sector.

For leisure travellers it is the starting point for lake-and-jungle trips, while business travellers use it as a base for regional government, trade and logistics near the border. Most visitors arrive overland from Managua, by lake ferry from Granada, or on domestic flights into San Carlos Airport.