Lake Coatepeque

The Coatepeque Caldera is a volcanic caldera in El Salvador, formed between 72,000 and 57,000 years ago due to a series of rhyolitic explosive eruptions from a group of stratovolcanoes. The caldera is surrounded by basaltic cinder cones and lava flows, as well as six rhyodacitic lava domes, with the youngest dome, Cerro Pacho, forming after 8000 BC. A large crater lake, Lake Coatepeque, is located in the east part of the caldera, covering an area of 26 square kilometers and featuring a Mayan site on an island called Teopan. The lake is known for changing its color from blue to turquoise due to a cyclical phenomenon, which has occurred several times since 1998.learn more on wikipedia