Towering more than 3,700 metres above sea level, Gunung Rinjani is one of Indonesia's highest mountains and a pilgrimage site to both Balinese Hindus and Sasak Muslims.
Rivers and waterfalls rush down its fissured slopes and feed a tapestry of rice paddies, tobacco fields and coffee plantations.
Inside its caldera is a fresh-water lake that changes in colour in accordance with the chemicals at work beneath its surface. Rising from the lake is the mountain's newest cone, formed by an eruption just a few hundred years ago.
Return treks to the summit are three-day affairs. Guides are mandatory and the going can be tough but the eventual rewards - weather permitting - are breath-taking views across Lombok and the Gilis, laid out like stepping stones towards Bali and beyond.