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. The lake pH is 7-8.
Gunung Rinjani National Park is located on the island of Lombok, Indonesia in the North Lombok Regency. The park covers about 41,330 hectares and consists of mountainous areas. Mount Rinjani (Gunung Rinjani), which is the third highest mountain of Indonesia (3,726 m), is located in this national park, giving this park its name.
There are also several endangered fauna protected in this national park, including rusa deer, indian muntjac, Sunda Porcupine, surili monkeys, Helmeted Friarbird, several cockatoos and Scaly-crowned Honeyeater.