Lake Toba is a large natural
lake occupying the
caldera of a
supervolcano. The lake is about 100 kilometres long, 30 kilometres wide, and up to 505 metres (1,666 ft) deep. Located in the middle of the northern part of the
Indonesian island of
Sumatra, with a surface elevation of about , the lake stretches from to . It is the largest
lake in Indonesia and also the largest
volcanic lake in the world.