Snorkeling Tips         
Underwater Wonders of the National Parks, published in 1998, is an indispensable resource for anyone considering a snorkeling trip. Written by Daniel Lenihan, director of the NPS Submerged Cultural Resource Unit, and John D. Brooks, an underwater photographer with the unit, the book details the watery wonders of the park system, from the coral reefs of the Caribbean to the icebergs in Alaska.
The two have gone snorkeling and scuba diving at every park mentioned in the book and include detailed suggestions on where to go, how to get there, and what you might find. They also have some sound advice for making your snorkeling excursion more enjoyable and helping to protect the fragile reef environment, including these tips:

• · Do not touch the animals. Even a gentle caress can disturb the mucous coating that helps protects fish from disease.
  Do not feed the fish. If fed by humans, after a while they become dependent on handouts and lose the ability to forage. Also, they lose their natural wariness, which makes them easy prey for poachers. Even though harvesting fish for tropical collectors is illegal in the national parks, it still goes on.
• · Do not touch the coral. The tiny jelly-like polyps that live inside the hard calcium casing are fragile. One swipe of the hand can kill hundreds of them. Many popular shallow reefs have been decimated by careless swimmers who stand on them when they get tired.
  Swim gently and avoid kicking up a lot of sand when near a reef. The sediment can eventually smother the coral and block vital sunlight.
• · Wear a liberal coating of waterproof sunscreen on your back and the backs of your legs. The thin film of water over you acts as a magnifier and because the water keeps your skin cool, you may not realize your skin is burning until it is too late. People who are especially sun-sensitive should wear a covering.
• · Keep an eye out for stinging organisms like jellyfish and fire coral.
• · Do not reach into holes or crevices in the reef. They could turn out to be the lair of a moray eel.
• · Take off your jewelry. While barracuda attacks are almost unheard of, the toothy fish do seem to be attracted to shiny objects.
• · Shark spottings are rare on the shallow reefs that snorkelers frequent, but if you see a shark, do not panic. Most reef sharks are passive types, not man eaters, and they usually ignore swimmers. If one acts aggressively or pays undue attention to you, calmly and slowly leave the water.
• · Do not walk in shallow water near the reef; sea urchin spines can cause nasty puncture wounds to the bottom of your feet.
• · Shuffle your feet across the bottom as you wade through the shallow sandy areas on your way to and from the reef. Stingrays lying on the bottom will swim off if you bump into them but sometimes sting when they are stepped on.
  Be aware of currents. Unless you plan to do a "drift dive" where you start in one spot and let the current carry you to an exit point, it's usually best to swim into the current first and then let it carry you back at the end of your dive when you are most tired.