South Iwo Jima is the southernmost island of the Volcano Islands group of the Ogasawara Islands, 60 km south of Iwo Jima. It is 1300 km south of Tokyo, 330 km SSW of Chichi-jima. Its area is 3.4 km and the shore length, 7.5 km. Along the shoreline there are few bays and inlets, and it is covered with mostly rocks and little sand. To the rear are sea cliffs that rise to 200 m in height. The peak on South Iwo Jima is the largest in the Ogasawara Islands at 913 m and its average slope angle is 45 degrees. The northwest side of this volcano, which has a relatively stable shape and is not eroding much, rises at a gentler incline of 30 degrees. Another defining feature of the island is that it does not have rivers, lakes, marshes or a freshwater system of any kind.