At 276 km2 Ometepe is the largest volcano lake island in the world. Island population is estimated at over 35,000 inhabitants. There are two principle villages on the island, Moyogalpa and Altagracia, both lake ports that serve routes from Granada, San Carlos and San Jorge. The island’s name is derived from its pre-Columbian, Mesoamerican lingua-franca original name in Náhuatl, derived from ōme 'two' y tepētl 'peaks' and with reason, since the island consists of two volcanoes Volcán Concepción and Volcán Maderas rising out of Lake Nicaragua and connected by a sandy isthmus.
The dominant mountain on the island is the perfect cone of Volcán Concepción (1610 m above sea level, 36.5 km in diameter). It is active and last spit out a good quantity of ash in the summer of 2009. Its last major lava flow poured out of the north side of the cone in 1957. The volcano was inactive for many years before it erupted back to life from 1883-1887, with frequent, lava filled eruptions. Concepción erupted 1908-1910, 1921 and 1948-1972. The volcano is currently a nature reserve protecting 5,400 acres of forest flora and fauna.
Volcán Maderas (1394 m above sea level, 24.5 km in diameter) last eruption according to local tradition was 800 years ago, scientists think it was much earlier, all agree that the cone is now extinct, though highly prone to mudslides. The mountain is wrapped in lush forest and is the site of only one of two cloud forests in the Pacific basin of Nicaragua. The summit holds a foggy and cold-water lake in its crater, Laguna de Maderas. The lake is 400m x 150m. On the western face of the cone there is a thin cascade called San Ramón. Maderas also is a nature reserve that protects 10,000 acres of tropical forest flora and fauna.