Waiowa, Volcano in Oro Province, Papua New Guinea

Waiowa, also called Goropu, is an isolated trachyandesitic volcano on New Guinea island in Oro Province, Papua New Guinea, 19 km inland from Collingwood Bay. It lies on a fault line along the northeast flank of the Owen Stanley metamorphic belt. Its summit holds a 500 m wide, steep-walled crater, now forested and containing a small lake.

The volcano erupted in September 1943 after months of seismic activity, continuing with repeated eruptions until August 1944. These events significantly altered the surrounding landscape.

The name Waiowa is paired with Goropu, the alternative name recorded for the mountain. The volcano lies in Oro Province, where the eruption of 1943–1944 broke through highly metamorphosed rocks of the Owen Stanley belt, and the forested crater and its small lake now sit within that terrain.

The site is remote, located about 19 kilometers inland from Collingwood Bay on the island's interior. Visiting requires proper planning and awareness of challenging jungle terrain and local conditions.

Waiowa is one of the world's newest volcanoes: it did not exist before September 1943, when eruptions broke through a layer of highly metamorphosed rock on the northeast flank of the Owen Stanley metamorphic belt. Its 500 m wide summit crater, now forested and holding a small lake, is younger than many of the trees around it.