Bagabag is an island in the Madang Province of Papua New Guinea having a dormant volcano. Bagabag is 43 km east-north-east from Cape Croilles on the northern coast of the Papua New Guinea mainland, and is the closest island to Karkar Island which is 18 km to the north-west. The island is approximately circular in shape, with a diameter of about 7 km. It has an area of 37 km². The prominent feature of the coast is New Year Bay, that cuts into the south-eastern side of the island. Volcanic in origin, terrain on Bagabaga consists of steep, thickly vegetated slopes that rise to over 600 m above sea level. Much of the northern, eastern and southern coasts are fringed by a barrier-type reef some 2 km offshore; the reef is narrow, and mostly submerged.