Cocos Island is an island 1 mile off the southern tip of the United States territory of Guam, located within the Merizo Barrier Reef, part of the municipality of Malesso'. The island is uninhabited, 1,600 meters long in a southwest–northeast direction, between 200 m and 300 m wide, and has an area of 386,303 m². It sits atop the southwestern coral reef rim of …Cocos Island is an island 1 mile off the southern tip of the United States territory of Guam, located within the Merizo Barrier Reef, part of the municipality of Malesso'. The island is uninhabited, 1,600 meters long in a southwest–northeast direction, between 200 m and 300 m wide, and has an area of 386,303 m². It sits atop the southwestern coral reef rim of Cocos Lagoon.