Geography

Largest and southernmost island in the Mariana Islands archipelago; strategic location in western North Pacific Ocean.

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 (January to June), rainy season (July to December); little seasonal temperature variation.

(From CIA Fact Book on Guam)