Snorkel Cades Reef

Fringing reef in Western Australia where whale sharks cruise close to shore.

Oceanic island off Borneo ranked among the best dive sites on Earth — turtles, barracuda tornadoes, reef sharks.

Granite-boulder islands in the Andaman Sea with some of Thailand’s clearest water and best coral.

The planet's richest coral reefs.

Ras Mohammed’s coral walls and the Thistlegorm wreck, with visibility so clear the reef looks lit from within.

Clear Caribbean sinkholes and reef right off the shore at Playa Giron.

Jordan’s slice of the Red Sea: coral gardens, a sunken tank and the Cedar Pride wreck in warm, calm water.

The largest reef in the northern hemisphere: nurse sharks and rays at Hol Chan, turtles and 500 species of fish.