At 3,726 m, Rinjani is the second highest volcano in Indonesia, second only to Mount Kerinci on Sumatra, and it dominates the landscape of the relatively small island of Lombok.
Within its huge 50 km² caldera sits the crater lake Segara Anak (Child of the Sea). Eruptions within the caldera have formed a new small cone called appropriately enough, Gunung Baru (New Mountain). Segara Anak has a natural hot spring.
The mountain and its satellites form the Mount Rinjani National Park (Taman Nasional Gunung Rinjani) – officially 41,000 hectares within the park boundaries and a further 66,000 hectares of protected forest outside.
In 2008, the Indonesian government proposed to UNESCO that Mount Rinjani be one of the world’s official geoparks. If this was approved by UNESCO, Mount Rinjani would become the first such geological park in Indonesia.