Segara Anak is a crater lake contained within Mount Rinjani on the island of Lombok in Indonesia. The name Segara Anak means child of the sea given to the blue colour of the lake reminiscent of the sea. The lake is heated, so its temperature is 20-22 °C, about 5-7 °C above the expected temperature for a lake in that altitude. At the west end of the lake is the volcanic cone Gunung Baru, giving to the lake a crescent shape. Gas bubbles escape from the lake floor.