Geography and Environment

Geography and Environment of Guam

Terrain, climate, natural resources, hazards, and environmental conditions of Guam.

Terrain: volcanic origin, surrounded by coral reefs; relatively flat coralline limestone plateau (source of most fresh water), with steep coastal cliffs and narrow coastal plains in north, low hills in center, mountains in south
Climate: tropical marine; generally warm and humid, moderated by northeast trade winds; dry season from January to June, rainy season from July to December; little seasonal temperature variation
Highest Point: 406 — Mount Lamlam 406 m
Lowest Point: Pacific Ocean 0 m

Natural Resources: Aquatic resources and fishing (largely undeveloped), tourism (particularly from South Korea, Japan, and the United States), and a significant U.S. military presence that contributes substantially to the local economy. Guam's surrounding waters hold considerable marine potential, though commercial fishing remains limited in scale. Tourism, while historically dominated by Japanese visitors, has diversified in recent years, with South Korean and other Asian travelers now making up a growing share of arrivals.
Natural Hazards: frequent squalls during rainy season; relatively rare, but potentially very destructive typhoons (June - December)

Current Environmental Issues: extirpation of native bird population by the rapid proliferation of the brown tree snake, an exotic, invasive species

Detailed geography