On the opposite side of Australia from the Great Barrier Reef lies Rowley Shoals, one of the ocean’s largest unspoiled coral reefs, with more than 200 species of coral and 600 species of fish. Formed by three pear-shaped atolls, the remote reef is one of few in the world affected by dramatic 16-foot tides, which push huge amounts of seawater in and out of the coral lagoons, creating a seascape like something out of Posiedon’s very own underwater world.