After Agung, Batur is the most sacred mountain on Bali. Most often the mountain's only sign of life is an occasional wisp of smoke that drifts across its lava-blackened slopes. But when this 1,717-meter volcano erupts, it glows red, bellows, and throws out rocks and showers of volcanic debris. If you arrive in Penelokan at night, you'll awaken to an unforgettable sight. The next morning, the mist will lift from the shining lake and roll across the crater like a mammoth white and gray curtain. When the weather is clear there are also spectacular views of Gunung Batur's smoking cone.
Sitting in the middle of an old volcanic basin inside a gigantic caldera, smoldering Gunung Batur rises 686 meters above Lake Batur. The crescent-shaped lake takes up about one-third of the basin's total area. Measuring 13.8 km by 11 km, this is one of the largest and most beautiful calderas in the world. The crater's outer walls, about 30,000 years old, range from 1,267 meters to 2,153 meters above sea level. There are actually two calderas; the floor of one lies 120-300 meters lower than the floor of the other. Plan on a full day to explore both of them.