About Guam

The map shows Guam, an island in the western Pacific Ocean. It lies about 60 km (37 mi) southwest of Rota, the southernmost island of the Northern Mariana Islands. Guam is the largest island in Micronesia, a subregion of Oceania, and the southernmost island in the Mariana Islands archipelago. The Commonwealth of the Northern Mariana Islands, Guam, and American Samoa lie along the western side of the famed Pacific Ring of Fire.

More about Guam


Located between the Philippine Sea and the Pacific Ocean, Guam sits roughly 2,100 km (1,300 mi) east of the Philippines and 1,800 km (1,100 mi) north of Papua New Guinea—on nearly the same latitude as Bangkok, Thailand.

The Mariana Archipelago traces the line of the Mariana Trench, the deepest part of the world's oceans (at Challenger Deep, estimated depth: about 10,984 meters (36,037 feet)). The vast underwater canyon marks an active subduction zone. It is the location where the massive Pacific Plate in the east is forced beneath the much smaller Mariana Plate and the less dense Philippine Sea Plate to the west.

Guam is an organized, unincorporated territory of the United States. Its capital is Hagåtña. Covering an area of 549 km² (212 sq mi), Guam is about the size of Hong Kong or three times larger than ashington, DC.

Guam's population is a vibrant mix of cultures and home to around 170,000 people (2025 est.). Pacific Islanders make up 46.1% of the population, including Chamorro (32.8%), Chuukese (6.7%), Palauan (1.4%), Pohnpeian (1.4%), and Yapese (1%). Asians comprise 35.5%, led by Filipinos (29.1%), followed by Koreans (2.2%), Japanese (1.4%), Chinese (1.3%), and other Asian groups (1.5%). The official languages are English and Chamorro, an Austronesian language.

Geography

Guam was formed by the collision of volcanic and limestone structures over millions of years. The island's base is composed of volcanic rock, which was formed by underwater eruptions. Over time, coral reefs grew on this volcanic base, and the accumulation of coral and other marine organisms led to the formation of limestone layers.

The rugged terrain of the island features forested mountains, coastal cliffs, and coral reefs that fringe much of the island.
The island sits near the tectonic edge where the massive Pacific Plate is pushed beneath the small Mariana Plate, which lies in front of the Philippine Sea Plate. It is a zone of intense seismic and volcanic activities.

Strategic Importance

Due to its location in the western Pacific, Guam holds significant strategic value for the United States. The island is home to key U.S. military installations, including Andersen Air Force Base in the north and Naval Base Guam at Apra Harbor, the island's deep-water port on the west coast. Off Guam's eastern and western shores lie designated Submarine Operating Areas (SOAs), undersea training grounds for Submarine Squadron 15, which operates nuclear-powered fast-attack submarines. Together, these military facilities form a vital forward operating hub for U.S. operations across the Indo-Pacific region, underscoring Guam's central role in maritime and undersea defense strategy.