On the northwest side of the lake, the Parque Eco-Arqueológico de los Naranjos is a Lencan archaeological site dating to approximately 700 BC. The ruins themselves are not terribly interesting; they’re made of clay so have only been semi-excavated (to protect them from environmental damage). The main reason to visit, however, is the wildlife. The park has 6km of trails that wind through the forest over hanging bridges and on a lakeside boardwalk, providing fantastic opportunities for spotting birds. A small museum at the visitors center gives a general overview of Lencan civilization, which is mildly interesting. The park is 5km south of Peña Blanca.