Mount Rinjani

Climb to the rim of Rinjani and the ground drops away into a vast caldera, roughly 6 by 8.5 kilometres, with a lake lying about 2,000 metres above the sea and, rising out of the water, a young dark cone of ash and lava. The lake is Segara Anak, named for its intense blue colour, and the cone is Gunung Barujari, the active heart of the volcano. Above it all the summit reaches 3,726 metres, the highest point of Lombok and of the province of West Nusa Tenggara, and the second-highest volcano in Indonesia.

The caldera is the scar of one of the greatest eruptions of the last two thousand years. In 1257 the neighbouring peak of Samalas, which once stood beside Rinjani, blew itself apart in an eruption ranked at VEI 7; its ash and gases were carried around the globe, and it has been linked to the cooling that led into the Little Ice Age. The lake, estimated at about 200 metres deep, fills the hollow that Samalas left behind. Since then activity has shifted to Barujari: every recorded eruption since 1847 has come from that small cone, including a sustained phase in 1994–1995, and hot springs still bubble up along the lake shore.

The mountain and its lake are sacred to the Sasak people of Lombok, who hold ceremonies there, and the whole massif is protected as Gunung Rinjani National Park, founded in 1997; in 2018 UNESCO added it to the Global Geopark Network. Most people see Rinjani on a trek of several days: through forest to the crater rim, down to the lake and its springs, and up in darkness to the summit for sunrise over the caldera.

Getting there

Rinjani rises in northern Lombok, about 27 km from the town of Selong. Lombok International Airport (LOP) is about 43 km away in a straight line, and considerably further by road. Treks start from the villages of Senaru, on the northern side, and Sembalun, on the north-eastern side,; the climb is usually made with local guides.