Tarakan is an island in the Kalimantan Timur province of Indonesia. It is a marshy island situated in the eastern Celebes Sea, off the northeastern coast of Borneo. The island occupies an area of 117 square miles (303 square km).
'Tarakan Lamo and Tarakan Itji (large and small Tarakan) have well-formed volcanic summit craters 800 and 500 m in diameter and 160 and 125 m deep, respectively. They are located near the shore of Galela Bay NE of Dukono volcano. The cinder cones lie between Galela bay and Lake Galela, whose bottom lies below sea level. Supriatna (1980) mapped Tarakan as a basaltic volcano of Holocene age.
Tarakan Island is situated off the delta of Sesa River in north-eastern Borneo.
Japanese strength at Tarakan was estimated at between 1500 and 4000 troops including l000 naval personnel.
Subsequent to the landing it was considered that the Japanese force on Tarakan consisted of 1750 combat troops plus 350 Japanese civilians who were impressed for military duty at the time of the landing.