Arnk ... arnk ... arnk ... the alarm wails as the glowing red numbers 5:59 transform into 6:00. I hit the ''off'' button and dress hastily in the dark. My wife, Jeanette, mumbles ''good morning,'' then rolls over and falls back asleep. As I ease the front door closed, the eastern sky is making the transition from black to gray. I follow the footpath to the pool, cut past the waterfront bar and make my way along the wharf to the dockside locker room. There, I begin the familiar ritual: cinch up the BC, add a regulator, slip into a wetsuit, grab mask and fins. It's time to go to work. The vacation part was going great, but with only two days left, I hadn't made dive one. Considering that our final day would be spent touring Washington-Slagbaai National Park, I was left with a mere 24 hours to sample all of Bonaire's underwater wonders. My one-day dive plan called for at least a half-dozen submersions at diverse locations around the island. The good news was that Bonaire is the one island in the Caribbean where such a dive profile is not only possible, it is actually fairly common. Wakeup Call A pair of early-rising parrotfish greet us as we enter the water in front of Captain Don's Habitat. We fin past the new pier and head for deeper water; the white sand below reflects just enough pre-dawn light to maintain bearings. The sea floor drops gently to 25 feet, then turns to shadow. From experience, I know this is the beginning of a coral-covered slope that plummets to 130 feet, and that a small wreck lies on the sandy plateau beyond. Were it later in the day, we would have dropped down the slope, spent a couple of nitrogen-rich minutes at the edge of the recreational envelope, then worked our way gradually up the slope. This morning, however, we limit our depth to 40 feet and investigate the many coral and sponge-encrusted nooks and crannies that line the reef. Slowly, the lights come on and the reef comes alive. A small moray eel emerges to test the waters, a school of blue tangs begin their morning commute, and a phalanx of snappers performs a wary about-face when confronted with my regulator's exhaust bubbles. This is Bonaire at its predictable best: easy entry, minimal current, abundant fish life and a reef tailor-made for multi-level diving - all within a stone's throw of the dive resort. The low-air alarm on my integrated computer jogs me back into the present. Hard to believe we've been underwater almost an hour. Silent Flight After stowing my gear and grabbing a quick shower, I still have time for breakfast with the family before catching the 8:30 dive boat. I return to the wharf, where Habitat's dive operations manager, Jack Chalk, and Walter Starke are loading DrAger rebreathers aboard one of the resort's Pro 42 dive boats. Photographer Walt Stearns joins us and we cast off and cruise north along the island's sheltered coast. Twenty minutes later, the boat is secured to the mooring buoy at a site named Karpata. Here, we find some of the most dramatic underwater profiles on the island, with vertical mini-walls that drop from 20 to 90 feet and beyond. It takes a couple of minutes to get used to the silence of the rebreathers - and to the lack of rise-and-fall when breathing - but in short order, we are soaring silently along a sponge-encrusted coral rampart. Starke hopes to share the silent wonder of rebreather diving with recreational divers. He recently he established a rebreather experience program that is available through Habitat and several other island resorts. This half-day program provides certified divers with a basic working knowledge of the Drager unit, then allows them to make an open-water dive on this closed-circuit dive equipment. The Drager delivers a rich 40-percent Nitrox mixture, so we have plenty of bottom time and plenty of breathing gas. In anticipation of my schedule, however, we limit the dive to an hour - 30 minutes deep, 30 minutes on top of the reef. A last-minute encounter with a friendly turtle stretches the dive to 80 minutes, but we still make it back to the dock in time for me to grab my conventional gear and step aboard the 11:00 boat. Shallow Stuff Uninhabited Klein Bonaire lies less than a quarter-mile offshore from the resort. By the time I reprogram my computer, we are tied to the mooring buoy at Rock Pile. With more than two hours of bottom time already under my weight belt, however, I take a little extra time planning my dive. I'm once again using Nitrox, but even with the benefit of extra oxygen, I decide to limit my depth to 50 feet and spend most of my bottom time in the shallows. Fortunately, we are at the perfect site for this type of profile. Rock Pile offers not only a coral-rich slope, but also some of the finest shallow reefs on the island. Sites on the southern side of Klein Bonaire were untouched by the storm swell from Hurricane Lenny, which wreaked havoc on portions of Bonaire's western shoreline. Today, the docks, dive shops and waterfront dining facilities at Habitat and other resorts have been restored and upgraded, and the only remaining evidence of the storm is a band of coral rubble in the nearshore shallows. At a depth of 10 feet, Klein Bonaire's reefs appear to be immune not only to storm damage, but also environmental degradation and human impact. Unbroken gorgonians and sea fans flutter in the surge and colorful fish weave through corals made vibrant by the mid-day sun. The health of Bonaire's reefs is no accident. Some two decades ago, Bonaire established an island-wide marine park, outlawed spearfishing, and began educating divers about no-impact diving. More recently, the government declared Klein Bonaire off-limits to development. These facts adds an extra enjoyment to my dive. Thanks to Bonaire's conservation policies, I know that my 3-year-old son will someday be able to experience the magical beauty of this same reef. Southern Exposure After lingering over lunch, Walt and I load our dive gear and extra tanks into a rental truck. With some 45 named sites and more than 25 miles of coastline accessible by road, Bonaire is ideal for shore diving. The rental vehicle of choice is a pickup truck fitted with a waterproof bedliner. We drop Jeanette and Nash off at Kralendijk's picturesque downtown waterfront, head south on the coastal road and turn left at the third yellow rock. Like other shore-dive sites, the wreck of the Hilma Hooker is marked by a hand-painted boulder set at the edge of the road. We gear up on tailgate, then make a short walk across the rocky beach and wade in through the gentle surf. A couple hundred feet out the reef drops into a 100-foot-deep sand trench. Locals decided this would be a perfect resting place for a 200-foot freighter named the Hilma Hooker. The wreck lies on its starboard side with masts and cargo booms intact. Her cavernous cargo holds provide shelter for a school of Bonaire's signature tarpon. We spend the majority of our bottom time photographing these 6-foot silver phantoms, then swim around the stern to surprise a huge cubera snapper near the upturned propeller. It is 3:00 p.m. when we surface. In deference to our nitrogen-soaked dive computers, we spend an hour wandering the beach a