Why Dive? To Be Keenly Alive in a Dreamland : DIVE: To Soar in Another World : DIVE: Follow Rules for Survival

PROVIDENCIA, Turks & Caicos Islands â€”  Megan is 10 feet beneath me, on the rim of the tropical coral reef that we have come to visit in our small boat. She is all legs and long, brown hair amid the multicolored fish, coral and sponges of this underwater world.

To our right, three table-size spotted eagle rays glide in formation like large pelicans over the sandy bottom. To our left, a multitude of tiny silverside anchovies creates a living wall of bright, shiny fish.

Above us is 50 feet of water, and beyond that a bright Caribbean sky. I float easily between the reef and the sky as the warm bubbles from Megan’s exhalations rise to bump against my bare skin like small, gentle fish.

In the face of each bubble, I see my own image reflected and backlighted by the sky above. It is the image of a man with flippers and mask and tanks, a man who is smiling so hard that his regulator is threatening to come loose in his mouth. It is a picture of a man quite deeply immersed in serious fun.

This is the world I know underwater, a place I have been visiting regularly over the last dozen years since becoming certified as a scuba diver.

A few years ago, a lawyer friend of mine asked me what it was about diving that was so exciting. I thought about the wonders I’d seen: the albino crayfish in the freshwater caves of Florida, the giant lobster in the wall crevices of deep blue Bahamian holes, the 18th-Century cannon on an obscure French wreck off Santo Domingo, the delicate, feather-like polyps emerging from the hard corals to feed at night on reefs everywhere.

I wanted to be able to provide a wonderful travelogue that would not only evoke the aesthetics of diving, but would also appeal to my friend’s sense of logic. Instead, I heard myself say: “It’s like flying.�

“Flying?�

“Yeah. Like in a dream. You know, weightless. Floating. Soaring over rooftops. That kind of stuff.� His expression was one of bewilderment tinged with pity. But it’s true. And while you can watch Jacques Cousteau until your skin wrinkles, you won’t really know what diving feels like until you do it yourself.

The coral reefs, wrecks, blue holes and caves I visit as an adult are a long way from my boyhood experience on Maryland’s eastern shore.

Inspired by early “Sea Hunt� episodes, a friend and I strapped on masks and headed out to explore he site of an old mill in a Wicomico County pond.

I remember the silt and the algae and the coldness of the water in late May, and wondering if I would find the mill stone before my toes were bitten off by a school of predatory mud turtles.

The thrill of discovery--the ultimate laying of hands upon the forgotten old mill stone--was a reward strong enough to make me almost forget that I had ever worried about minor inconveniences such as cold or slime or missing toes. Someday, I was sure, I would find out more about this business.

Today, after hundreds of dives in fresh and salt water, I have no trouble getting as excited as I did during my first descent. And I’m a little surprised more travelers haven’t discovered the joys of underwater tourism.

After all, diving not only helps you escape Melville’s “terra firma toils and cares,� it tweaks the senses, opening the door to discovery and to experiences that are as authentic as they come.

Last winter when I flew to the Caicos Islands for a week of diving, my expectations were as open-ended as they come.

Megan Davis, a biologist who works on Providenciales Island, and I commandeered a small wooden skiff from the conch farm where Megan works, and puttered down the coast to a small seaside dive shop where we picked up fresh tanks of air. Then we headed a mile offshore to the island’s barrier reef and anchored.

We spent the rest of the afternoon floating weightlessly in a world where each color and movement seemed fresh and new. Our only links with onshore realities were our dive watches and our air pressure gauges, and even they seemed tenuous at times. Which brings me to a fundamental part of the diving experience.

Before you take the plunge, there are rules to learn and obey. These are not polite guidelines, such as staying on your side of the court in doubles. These deal with such necessities as breathing and knowing when to come home.

All these laws are based on the fact that we, and not the little multicolored fishes, are the alien beings in an environment in which our status as more advanced land mammals counts for nothing.

Divers learn about these survival skills through basic certification, a 30- to 40-hour course that combines classroom work with in-water instruction, and which includes written and open-water tests.

Here, divers are introduced to basic rules of safety, learn about their equipment and how to use it.

The courses, which have become nationally standardized through half a dozen certifying agencies, teach divers how to act under water and emphasize the need to be aware of decompression realities--length of bottom time, time between dives and safe depths--by studying the U.S. Navy Diving Tables. Most divers carry copies of those tables with them to constantly figure safe limits of descent.

A critical part of the training is learning to select and use underwater gear. This includes a tank holding compressed air (not oxygen); a regulator that feeds air on demand from the tanks; a pressure gauge to measure remaining air; weights to compensate for air displacement by your tank or wetsuit; a buoyancy compensator vest to stabilize your underwater buoyancy by adding or removing air, and a good set of fins, snorkel and mask.

Depending on the brand, you can outfit yourself from about $600 on up. With new underwater gadgets, such as a hand-held computer to figure decompression needs on the spot, final costs can exceed that figure by three times or more. Used gear is far cheaper, but it takes a trained eye to spot deficits or flaws.

At the same time, there is a danger of becoming too dependent on your spiffy, new upscale gear. According to the National Centers for Disease Control in Atlanta, almost all dive-related fatalities are the result of diver error, rather than equipment failure.

During certification training, you will learn some primal truths that you will be unlikely to forget. Such as: Never surface faster than your bubbles. Or, never hold your breath with compressed air in your lungs. Bad things happen here, like air embolism, thoracic squeeze and the sort of things you see going on in a sci-fi movie.

Scary? Sure. But the great beauty of certification is that it imparts a sense of confidence under water. When my regulator blew out a small gasket and started feeding me water instead of air just as I hit the 90-foot mark in the Gulf Stream off West Palm Beach a few years ago, my next reaction was fairly critical.

I could turn blue and sputter, thereby ending my diving career on the spot. Or I could signal the nearest diver and relying on his largess and his air, proceed to “buddy breath� from his regulator until we reached the surface.

I wish all decisions in life were that simple.

The major instruction agencies--NAUI, PADI, NASDS, YMCA, and SSI--together certify half a million new divers a year through local dive shops, college courses, and dive resorts. Although all courses offer in-water training, domestic shops outside of Florida or California often use a nearby quarry or murky local waters for check-out dives.

Since I earned my own certification in clear warm coastal waters, I’m sold on the idea of learning how to dive at a shop or resort in the more inviting waters of the tropics.

Thanks to policing within the dive industry on the part of shops and charter boats, it’s nearly impossible these days to rent equipment, have your tank filled with air, or get on a dive boat unless you have a C (certification) card.

What you do after you learn to dive depends on where your interests lie. Florida and California, most of the Caribbean and the South Pacific, Australia and Central America are great for diving, as are many locations in Europe, as well as the Red Sea and the Mediterranean.

In the Caribbean, the best diving is off those undeveloped islands where people pressures have not yet polluted the clear, warm tropical waters. Ironically, even those spots unspoiled by heavy commercial development may suffer from their own dive-related success when flipper-wearing hordes regularly begin regularly descending on local reefs.

Regardless of where you go, the trick is to find dive charters that visit out-of-the-way spots and that carry only a few divers--certainly no more than 10--on board.

Belize and the island chain of the Turks & Caicos are especially known for spectacular wall-diving, in which the sea floor drops from 70 to 80 feet down to 1,000 fathoms or more in the course of a few yards. The experience here is akin to jumping off the edge of a tall building and hovering in the air.

While the smaller outer islands of the Bahamas, such as Eleuthera, are less crowded than New Providence or Paradise islands, you don’t need to travel to remote spots to find good diving. There are still great patches of water closer to larger islands such as Grand Bahama, where a number of deep, circular sinks known as blue holes dot the shallow white flats offshore.

Other well-known Caribbean dive locales include the Caymans, Bonaire, Barbados, the British and U.S. Virgins, Mexico (except for the Gulf) and the islands off Honduras, such as Roatan. Most of these islands feature complete packages for divers that include unlimited diving, accommodations and gear.

Charter boats known as live-aboards are another popular option for divers. Once Spartan floating dorms, the live-aboards have evolved into luxurious cruise boats with air-conditioned rooms, video facilities and tasty cuisine.

There are a number of things we divers do to amuse ourselves. Some of us use underwater cameras to try to capture the ambience on film. Others look for mint-condition shells, the kind that haven’t yet been dulled by a pounding surf. Still others hunt for edible fish with spear guns.

One of the best meals I ever had was a bouillabaisse I helped make at a friend’s house in the Turks & Caicos, using grouper and fresh conch meat only a couple hours out of the water.

But, while I have dabbled in such things, I’m more than content to simply look, and learn to identify the wonderful shapes and forms I see on the other side of the looking glass: the flamingo tongue shell with its orange spotted mantle extended to feed; the blue-gold fairy basslet; the Day-Glo black French angel; the Volkswagen-shaped brain corals.

Dali, on his best day, couldn’t have dreamed this stuff up.

In the best of worlds, the underwater experience ought to be far more than just a consumptive one for us all. Spearfishing and shell-collecting should be practiced with a great deal of discretion, and divers should never remove live coral.

Even sloppy diving, the kind in which novice divers wallow on the bottom instead of gliding over it, can be disastrous for the fragile polyps brushed by an errant flipper.

And it doesn’t take a trained biologist to see how quickly the reef reacts to poor treatment: Dead white patches in the coral appear within weeks of damage; a few months of heavy spearing may take years to replenish.

Although pollution from shore, ship collisions and oil spills are major threats to dive sites worldwide, one of the most consistent forms of damage comes from sport divers themselves.

For that reason, there is a growing trend toward setting protective laws to keep the fragile reefs from being “over-loved.�

For instance, the British Crown Colony of the Turks & Caicos Islands in the Caribbean has established a series of underwater national parks where the removal of even rocks and sand is illegal.

This little island nation, 90 miles north of Haiti, has also been a leader in the region in promoting “non-consumptive� diving. As a result, spearfishing while using tanks has been outlawed for more than a decade, and even the taking of live shells with scuba is prohibited.

The same rules apply in the underwater John Pennekamp Coral Reef State Park off Florida’s Key Largo. The signs there warn: “Take only pictures, leave only bubbles.�

Also in the Florida Keys, where the North American continent’s only coral reef system runs just a few miles offshore in the Atlantic, lawmakers are preparing to set aside a large area as a “marine sanctuary.�

In Key West, meanwhile, a nonprofit group known as Reef Relief is working with dive shops to educate sports divers to the fragile reef ecosystem. Reef Relief has also attached several dozed mooring buoys to the sea bottom near popular dive sites so that charter boats can tie up to the buoys instead of dropping anchors and thereby harming the living coral, sponges and sea grasses below.

Not everyone will find complete comfort in the underwater experience. Even those with a deep-seated desire to return to the sea may have problems if they rush through certification courses or don’t stay in reasonable shape for future dives.

But for the folks who want to give it a try, the journey into the underwater world can provide a sort of a trip within a trip.

It’s a journey to a place where spotted eagle rays glide like pelicans, where a little fish called a fairy basslet hides in the corals, and where men and women really can fly.