The surface of New Britain is dominated by a number of large volcanoes. From the westernmost part of the island to its northeastern promontories in the vicinity of Rabaul, these volcanoes form the more elevated parts of the skyline, but their slopes often coalesce in the interior and reach the sea toward the periphery of the island. The higher peaks rise to elevations of 7000 to 9000 feet, and with infrequent exceptions the insular divide stands above 4000 feet. In the northeast recently active volcanoes ring the magnificent natural harbor of Rabaul and the city of Rabaul, which until its complete destruction in the early Pacific phases of the Second World War was the finest port and largest city of northern Melanesia as well as the capital of the Mandated Territory of New Guinea. This was the second time within a decade, incidentally, that the city had suffered destruction, volcanic explosions late in the 1930's accounting for the earlier catastrophe.
The lowlands of New Britain are small, scattered, and coastal in distribution except where a few valleys extend into the interior in the eastern part of the islands. In consequence of this and the wet, cloudy climate of the higher elevations in the interior, most of the population is strung out along the coasts or concentrated in a few widely spaced villages at or near the coast. Plantations have a similar distribution, mostly because of the unfavorable climate and steep slopes of much of the interior. In the east, where the topography is somewhat more favorable for cultivation, plantations and native gardens extend well into the interior in spots.
New Ireland is somewhat more favored by topography as far as settlement and agriculture are concerned, being in general lower and, in the vicinity of the coasts, rather flatter and drier. Its crestline is dominated by metamorphosed sedimentary and igneous rocks rather than massive, solitary volcanic cones. The coastal plains that fringe the island, especially on the west, are narrow but fairly continuous and on the whole rather well suited to coconut plantations, the principal industry of the islands.