Tarakan is a triangle shaped island off the coast of Borneo. The island is roughly long from its northernmost point to the southern tip and wide towards the north of the island. The small island of Sadau is located about off Tarakan's west coast. Almost all of Tarakan's coastline is swampy, and in 1945 mangroves on the northern half of the island stretched to inland. The coastal mangroves in the southern portion of the island were narrower. Inland from the swamps, most of central Tarakan comprised a series of steep and densely forested hills just over high. Tarakan is located three degrees north of the equator and has a tropical climate. The maximum temperature for most days is about 90 degrees Fahrenheit, and relative humidity is consistently high at about 90%.