Lake Segara Anak

Segara Anak, "child of the sea", is the crescent-shaped blue lake that fills much of the great caldera beside Mount Rinjani on Lombok, and its name refers to a colour that recalls the ocean. It lies at about 2,000 metres above sea level inside an oval basin some 6 by 8.5 km, and reaches about 230 metres at its deepest.

The caldera is the scar of one of the largest volcanic eruptions of the last few thousand years. In 1257 Mount Samalas, which is thought to have stood around 4,200 metres high, blew itself apart, ejecting enough ash and sulphur to leave traces in polar ice cores and cool the global climate for several years; some researchers link it to the onset of the Little Ice Age. The mountain's remains are the caldera rim, and the lake gathered in the hollow. From its eastern shore rises Gunung Barujari, "the new mountain", a young volcanic cone, active in 1994–95 and again in 2010, whose lava flows give the lake its crescent shape.

Because magma lies not far beneath, the water is several degrees warmer than a lake at this altitude should be, around 20–22°C, and gas bubbles rise from the bottom. The lake had no fish until 1985, when the provincial government stocked it with tilapia and carp, and fishing is now a local livelihood. For trekkers on Rinjani the lakeshore, with Barujari opposite and the summit of Rinjani, at 3,726 metres, above, is one of the great moments of the climb.

Getting there

The lake lies within Gunung Rinjani National Park and is reached only on foot, on multi-day treks from the villages of Senaru, the easiest route, or Sembalun. Selong, the nearest town, is about 31 km away, and Lombok International Airport (LOP) is about 42 km away in a straight line.