Micronesia : Guam

This island, officially called the US Territory of Guam, is the largest and most southernmost of the Mariana Islands. Its capital is Hagatna, formerly Agana. It has been a US territory since 1898, apart from three years, 1941-44, when it was taken over by Japan during WW2. It still remains one of the most strategically important US military bases in the Pacific.

Almost all the diving is found on the west coast and can be split into four main areas - Agat Bay, the south coast, the northwest coast and Apra Harbour. Despite a booming tourist industry and military presence, diving can be extremely rewarding here. There are some 400 species of coral and 900 species of fish to be found. There's plenty of big fish action and visibility is excellent. The presence of numerous WW2 wrecks adds to the island's appeal and the overall convenience of travel to the various sites further increases its popularity.

The famous Marianas Trench lies just off the east coast and The Challenger Deep, the deepest point on earth at 10,911m, is to the southwest.

Certainly, there are serious environmental issues that have adversely affected the coral reefs and fish population around the island, with the main dangers being from pollution, silt erosion and overfishing. However, a number of marine preserves have now been set up to closely monitor the ecosystem and the situation is improving.