From San Carlos you can catch a boat and reach El Castillo De La Imaculada Concepcion, a town rising near an old fortress built by Spanish in 1675 to watch over the way to Cocibolca and protect Granada and the other cities situated on the lake.
The rises approximately in the middle point between the lake and the Caribe See. Tourists can explore the fortress, walkinkg along its narrow street, and visit its interesting museum that helps to understand the importance Rio San Juan had in past.
You can choose to stay in the lodgings or go and fishing the biggest tarpoons or goon an excursion to canoe enjoying the real magic of the tropical forest.