Gunung Rinjani is a top attraction on Lombok. Rinjani itself does not see the eruptions and activity that some of the others have, but its caldera-forming eruption in the late 13th century is believed to have been one of the most powerful in human history. A lake sits in Rinjani's caldera, and within the lake sits Mt. Baru, another active volcano. In Rinjani National Park, you may spot animals such as the rare black Ebony leaf monkey, long-tailed macaques, the sulfur-crested cockatoo, and other exotic species. Guided treks are available, and you can camp overnight in the park. The park does caution that treks are strenuous, so if you plan to hike the mountain, you should be in good physical health and be prepared with the appropriate equipment.