To enjoy the magnificent coral reefs and profusion of marine life surrounding the islands of Zanzibar, take a boat -- or a walk. At low tide in the spring, when the sea recedes more than a mile from shore, even non-swimmers can encounter growing corals, sea urchins, blue-spotted stingrays, octopus, sea cucumbers and moray eels. Just wear protective shoes and be sure to get back before the tide comes in!

About 65 genera of coral grow in the Indian Ocean, well over twice as many as in the Caribbean. Beautiful fish abound. The Indian Ocean offers some of the richest snorkeling and scuba diving in the world. Off the coast of Zanzibar Island (Unguja) and its less accessible neighbor to the north, Pemba, lie miles of shelf reefs known as fringing reefs. The environment offers near-perfect conditions for coral, which grows near the surface of very warm water, at least 65° F, and within 30° north or south of the equator. Located at latitude about 6° south, Zanzibar was destined to become a snorkeling mecca.

Although corals have been around for 500 million years, the coral reefs we know today were born only 5,000 years ago. In part, they have resulted from sea level changes during the last two ice ages. Sea levels rose 100 meters about 15,000 years ago and another 20 meters 7,000 years ago. As most corals live only near the surface, such changes in sea water levels have drowned numerous coral reefs around the globe and have allowed the formation of new, radiantly colorful reefs near islands like the Zanzibar archipelago.