Lording over the northern half of Lombok, the active Gunung Rinjani (3726m) is Indonesia's second-tallest volcano. It's an astonishing peak, and sacred to Hindus and Sasaks who make pilgrimages to the summit and lake to leave offerings for the gods and spirits. To the Balinese, Rinjani is one of three sacred mountains, along with Bali's Agung and Java's Bromo. Sasaks ascend throughout the year around the full moon.

The mountain has climatic significance. Its peak attracts a steady stream of swirling rain clouds, while its ash emissions bring fertility to the surrounding crops of rice, tobacco, cashews and mangoes.

Rinjani also attracts many trekkers who thrill to the otherworldly vistas. In fact the volcano has become so popular that the number of annual trekkers now exceeds 100,000.