Guam is an island in the western Pacific and the territory of the United States. The island is the largest and southernmost of all the Mariana Islands. Guam’s economy is largely dependent on tourism (mostly from Japan) and U.S. military bases. About 163,000 people live in Guam. Its area is 540km2. The highest point is at 406m. On December 7, 1941, a few hours after the attack on Pearl Harbor, Guam was captured by the Japanese, who occupied the island for two and a half years. American forces reconquered the island on July 21, 1944. In recent years, several marine reserves have been established to protect the fish population.