This volcanic crater, 30km north of Bandung, has a flat, elongated summit that resembles an upturned boat (prahu ). It's a huge tourist attraction and certainly a spectacular sight, but also something of a tourist trap. If you do decide to go, try to aim for early in the day as by noon the mist starts to roll in.
It's possible to circumnavigate most of the caldera on foot, but as wannabe guides can be aggressive and tourists have been robbed, there are better places for a highland walk.