Misima (formerly called St. Aignan) is a volcanic island in the northwest of Louisiade Archipelago within Milne Bay Province of Papua New Guinea.

Misima island owes its name to Élisabeth-Paul-Édouard de Rossel, which was a lieutenant of the Counter admiral Antoine Bruny d'Entrecasteaux during his journey of scientific exploration.

[2] By March 1889, eighty men were on the island digging for gold, and a storekeeper had set up a business.

Koia Tau, at a height of 1,036 meters (3,399 ft), is the highest peak of the Louisiade Archipelago.

In March 2012 Barrick closed its post closure monitoring office in Bwagaoia having successfully rehabilitated the mine and mill sites.

Other sources of income, especially for people living on the north coast, are cash crops of coconuts, copra, and cacao.

(Misima has a working airport (IATA: MIS, ICAO: AYMM) (four flights weekly to the mainland (POM via Alotau) through Airlines of Papua New Guinea, and one charter run by Porgera Joint Venture), a high school (grades 7-12), a small market, a few small stores and a clinic/hospital, a post office,--all of which are located in Bwagaoia.

There are ferries from Alotau which service Misima Island, costing around K100 (update 2024: K150-K200)and taking 17 (17-19) hours.