Guam lies between 13.2°N and 13.7°N and between 144.6°E and 145.0°E, and has an area of 212 square miles (549 km2), making it the 32nd largest island of the United States. It is the southernmost and largest island in the Mariana island chain and is also the largest island in Micronesia. This island chain was created by the colliding Pacific and Philippine Sea tectonic plates. Guam is the closest land mass to the Mariana Trench, a deep subduction zone, that lies beside the island chain to the east. Challenger Deep, the deepest surveyed point in the Oceans, is southwest of Guam at 35,797 feet (10,911 meters) deep. The highest point in Guam is Mount Lamlam at an elevation of 1,334 feet (407 meters).