The St Matthias Islands (also known as the Mussau islands) are a small group of islands in the Bismarck Archipelago, that makes up part of Papua New Guinea. They are part of New Ireland Province.
There are at least 10 islands. The largest and most northerly is Mussau; grouped with Mussau on its southwest are Eloaua, Emananus, Boliu, Emussau, Ebanalu, Ekaleu, and a few smaller isles; Emirau lies to the east and further east again is Tench Island. The islands have been designated as an Endemic Bird Area by Birdlife International.
Coordinates: 1°35′S 149°49′E / 1.583°S 149.817°E