Shimojima is a small island in the Japanese Guangulie Islands, located at the southernmost point of the Ryukyu Islands, the first island islands to the north east, about 24 degrees 49 minutes north latitude, 125 degrees 8 minutes east longitude. The island is northwest to southeast, about 5,000,500 meters long, about 2,700 meters wide, less than 15 square kilometers. The island's economy is backward, the population is no more than 8,000, natural resources are very scarce, sometimes even fresh water is difficult to supply.