Which capital city is the only one located on the island of New Guinea?

Port Moresby is the only national capital city located on the island of New Guinea.

It is the capital and largest city of Papua New Guinea, on the island’s southwestern coast beside the Gulf of Papua. Papua New Guinea occupies the eastern half of New Guinea; the western half belongs to Indonesia. Port Moresby became the capital of the independent country in 1975.

The city was named after Royal Navy Captain John Moresby, who encountered the area in 1873 and named it for his father, Admiral Fairfax Moresby. During World War II, its position made it a major Allied base and a Japanese military objective.

Jayapura is a common mix-up because it is also on New Guinea, but it is the provincial capital of Indonesia’s Papua province rather than the capital of a sovereign country. Suva and Honiara are national capitals, but they lie on different Pacific islands.