By Mark Leger, GORP Editor Snorkeling a coral reef will teach you more about biological diversity than any number of nature documentaries.
Coral reefs abound in warm, shallow tropical waters.
They're one of the most biodiverse environments on the planet, and one of the strangest to us air-breathing terrestrials. Hard coral, which forms rigid skeletons of calcium carbonate, create the reef's basic structure. The coral's color derives from algae, which lives symbiotically with the coral, supplying nutrients and oxygen in exchange for a growing surface. Octopuses, sea urchins, eels, spiny lobsters lurk in the coral crevices, while colorful tropical fish swirl throughout this hallucinogenic panoply. It's like landing on another planet.