Balbi volcano forms the highest point on Bougainville Island and is part of a large number of coalesced cones and lava domes. Five well-preserved craters occupy a NW-SE-trending ridge N of the summit, which also has a crater. Crater C, containing a small lake, is seen here from the E. A plume from a fumarole field on the W flank of 600-m-wide Crater B is visible to the left. The latest eruption may have been as recent as the mid-19th century. Photo by Wally Johnson, 1987 (Australia Bureau of Mineral Resources).