Mount Rinjani is an active volcano on Lombok, Indonesia. It rises to 3,726 m (12,224 ft), making it the third-largest volcano in Indonesia. The first historical eruption occurred in September of 1847. The volcano, and its sacred, Segara anak crater lake, are protected by a national park in 1997. The 6 km by 8.5 km oval-shaped caldera is filled partially by a lake known as Segara Anak.
The challenging three-days or four-days Rinjani Trek route from Senaru to the stunning crater rim (Plawangan), down to the stunning crater lake then on to Sembalun Lawang, is considered as one of the best treks in South East Asia. Those heading for the summit usually prefer to start from Sembalun Lawang. A model for ecotourism in Indonesia, the community-based activities are focused on the Rinjani trek Center in Senaru, the most popular starting point for the tough trek.