It is separated from New Guinea by a northwest corner of the Solomon Sea (or with an island hop of Umboi the Dampier and Vitiaz Straits) and from New Ireland by St. George's Channel.

Steep cliffs form some sections of the coastline; in others the mountains are further inland, and the coastal area is flat and bordered by coral reefs.

The Nakanai Range in East New Britain is composed largely of limestone karst, which extends from the mountain peaks to the southern coast.

It comprises the mainland of two provinces: In research science, there is evidence with Pleistocene-era cultural deposits discovered in open-site excavations in near Yombon, which show that New Britain has been inhabited by indigenous Papuans for thousands of years, with human occupation dating back to 21,000 BC.

The expatriate population was practically confined to the northeastern Gazelle Peninsula, which included the capital, Herbertshöhe (now Kokopo).

At the time 5,448 hectares (13,460 acres) had been converted to plantations, primarily growing copra, cotton, coffee and rubber.

Westerners avoided exploring the interior initially, believing that the indigenous peoples were warlike and would fiercely resist intrusions.

On 11 September 1914, New Britain became the site of one of the earliest battles of World War I when the Australian Naval and Military Expeditionary Force landed on the island.

Strategic bases at Rabaul and Kavieng (New Ireland) were defended by a small Australian detachment, Lark Force.

New Britain was invaded by the U.S. 1st Marine Division in the Cape Gloucester area of the very western end of the island, and also by U.S. Army soldiers at some other coastal points.

Much of the story from the Japanese side, especially the two suicide charges by the Baalen group, are retold in Shigeru Mizuki's Onward Towards Our Noble Deaths.

The factual telemovie Sisters of War recounts experiences of Australian Army nurses and Catholic nuns during the conflict.

The Papuan population is largely confined to the eastern third of the island and a couple of small enclaves in the central highlands.

Forests on New Britain have been rapidly destroyed in recent years, largely to clear land for oil palm plantations.