Rinjani (3726m/12,221ft) is the highest mountain in Lombok. It's an active volcano - it last erupted in 1995 - and a popular destination for hikers and locals making pilgrimages to the hot springs located on the north-eastern side of the caldera. The springs are thought to have amazing curative powers. A lake is 600m below the rim of the crater, and a relatively new cone, Gunung Baru has grown out of one side. Four-day treks to the caldera are common, but care should be taken as the tracks are often slippery.