Located 146 nautical miles north from Saipan and 4.4 square miles in area. The island's volcano has a large crater at the summit. The west side is cut by deep gorges covered with high savanna grass. The southeast side is a steep slope of bare lava. There are deep valleys with caves. Coconut palms grow on the gradual slopes. Warm fresh water springs are located on the northern part of the west coast.
Highest point 2,441 ft.