Kusaie, which is located in a position approximately 5° 20′ north latitude and 163° 00′ east longitude, is the easternmost of the Carolines and the third in size. The island is roughly 8½ by 10 miles, with an area of about 42 square miles. The main part of Kusaie is made up of two rugged basaltic mountain masses whose sharp ridges and V-shaped valleys are characteristic of a youthful stage of erosion. Mount Buache, elevation 1943 feet, occupies the northern part of the island and is separated from the southern mountains by a low valley. The southern range forms a compact mass in the center of the island with numerous peaks. Mount Crozer, elevation 2061 feet, is the highest. Both mountain masses are surrounded by an alluvial coastal plain of varying width. The coastal plains have a dense cover of mangrove and coconut palms. The mangrove swamps are so dense that landing is difficult except where they have been cleared. Back of the mangrove there is a belt of coconuts, mango, and breadfruit trees. There are patches of nipa palms at the mouths of the streams.
Most of the original forest that occupied the interior has been destroyed and replaced by a secondary forest of trees 30 to 40 feet high. These are mixed with shrubs to produce an almost impassable tangle. There are some openings with a high grass cover.
The chief occupations of the natives are subsistence agriculture and fishing. Some copra is exported. The Japanese started a small sugar plantation that has been abandoned since the American occupation. This also happened to the fishing industry, which had been started by Okinawans with motor sampans.
The native houses are rectangular in form, and the better ones built on raised stone platforms. There are ruins of a stone city on Lele Island that are similar to the stone ruins at Nan Matal on Ponape. These consist of walls built from large basaltic columns, rising in places to a height of 20 feet.