Rabaul was the capital of East New Britain province, Papua New Guinea until 1994. It was built within the caldera of a large volcano, and was always vulnerable to an eruption. In 1994, a particularly large eruption took place. Two of the vents on the rim of the caldera, Tavurvur and Vulcan, erupted in September of 1994, destroying the airport and most of the town with heavy ashfall. The new capital, Kokopo, is just 20km away, so the region (and new airport) is still most often referred to as Rabaul.
Rabaul has good diving and snorkeling sites and a spectacular harbour, and so was slowly becoming a popular tourist destination before the eruptions. There are still several diving operators based there.
During World War II Rabaul was a major Japanese base and there is still much military debris in the harbour, on the land and under the hills—the occupying Japanese army dug many kilometeres of underground tunnels as shelter from the Allied air forces.
After taking off from Rabaul on April 18, 1943, Admiral Yamamoto Isoroku, the architect of the Japanese attack on Pearl Harbor, was shot down and killed by U.S. fighter planes which were hastily dispatched after decryption of Japanese communications describing Yamamoto's flight itinerary.