Geographically, Bougainville is the principal island of the northern group of the Solomon Islands archipelago. It is about 190km long and 50km wide and is a place of great natural beauty. There is a spine of steep mountains running north to south, some higher than 2,500m.
The mountains include a number of volcanoes. Seventeen post-Miocene strato volcanoes have been identified on Bougainville, the largest island of the Solomon Group. From north-west to south-east, these are the Tore, Balbi, Numa Numa, Billy Mitchell, Bagana, Reini, and Bakanovi volcanoes and the Takuan and Toroka groups of volcanoes. There are several other post-Miocene volcanoes in northern Bougainville which have not been accurately delineated.
Three of the volcanoes are active or potentially active; these are Bagana, the most active volcano in the Territory of New Guinea, and the dormant Balbi and Loloru volcanoes.