The climax of an unforgettable trek, the nation’s second-highest mountain (after Sumatra’s Gunung Kerinci) is a sacred volcano, revered equally by Lombok’s Sasak Muslims and Bali’s Hindus, who each year come to throw offerings into the large crater lake, Danau Segara Anak, a lovely cobalt-blue crescent... The climb (from Senaru, for fit walkers only) takes from 2 to 4 hours, depending on whether walkers stop at the edge of the caldeira, head down to the lake or continue to the summit (3 726m).