The Bacan Islands (Dutch: Batjan), formerly also known as the Bachans, Bachians, and Batchians, are a group of islands in the Maluku Islands of Indonesia. Bacan Island is that group's largest island. The islands are mountainous and forested. The islands lie south of Ternate and west of Halmahera's southernmost arm. Bacan itself is the largest; the second and third largest islands are Kasiruta and Mandioli.