About 130 km (81 mi) southwest of the township of Rabaul, Ulawun is the highest mountain in New Britain and the second in the Bismarck Archipelago at 2,334 metres (7,657 ft), and one of the most active volcanoes in Papua New Guinea.

Because of its eruptive history and proximity to populated areas, Ulawun is considered one of the Decade Volcanoes.

The last few years have seen almost constant activity at Ulawun, with frequent small explosions, and have caused great damage and loss of life.

[3] On 20 November 2023 ash emissions and eruption noises lead to the alert level being raised to stage 3.

[6] Recent studies have shown that Ulawun alone releases about 7 kg/s of SO2, which is about 2% of the global total of SO2 emissions into the atmosphere.