Misima (formerly called St. Aignan) is a volcanic island in the northwest of Louisiade Archipelago within Milne Bay Province of Papua New Guinea. The island measures 40 km by 10 km and has an area of 202,5 km². It is located some 20 km north of the northwest extreme of the barrier reef of Vanatinai at Isu Raua Raua Island, and 80 km northwest of Vanatinai Island itself. Misima is mountainous and densely forested. Mt. Koia Tau, at a height of 1,036 meters, is the highest peak of the Louisiade Archipelago.