There is something special about diving on the edge of a plunging marine precipice. Even with a vast accumulation of dives under my belt, I am still awed by the spectacle of a world falling abruptly into absolute nothingness. Akin to the dramatic precipices that have made both the Cayman Islands and Belize's Lighthouse Reef famous, the walls fringing the Turks & Caicos Islands run a variable range of profiles. Whereas one site can be as vertical as they come, plunging straight off into the abyss, the next site 100 yards away may follow more of a cascading descent. From Provo's Northwest Point down to West Harbour Bluff, most dive sites begin their tumultuous drop between 40 and 60 feet. Some of these drop-offs include a series of short, vertical embankments that extend as far down as 180 feet before making the big plunge to the ocean floor 6,000 feet or more below. Hanging stationary against a backdrop of vivid blue created by the open waters of the Atlantic, I dump the last remaining air from my BC and execute a short free-fall past the vaulted crest of a shadowy wall. Descending at a speed comparable to a leaf floating to earth, the sight of the wall's scalloped face ticking past is a genuine rush. Beneath one broad undercut large enough to harbor a bus, a collection of rope sponges and wire corals hang from the ceiling like tangled party favors. Nearby are the entrances to two chimneys that descend about 50 feet. Emerging from the exit of one of these tunnels, I look up. The wall's serrated crest, back-lit by the brilliant late-morning sun, is even more evident. Just beyond it, Provo Turtle Divers' 42-foot Newton dive boat looks small and dainty. Art Pickering, who owns Provo Turtle Divers, is known as somewhat of a legend in the Turks & Caicos. In addition to establishing the region's first water-sports operation, he discovered and named most of the dive sites around Provo and West Caicos. In addition to the Newton dive boat that is equipped with a pair of freshwater showers, Turtle Divers has a 30-foot Island Hopper. The two charters routinely take divers as far north as Parrots Cay off North Caicos, around to Provo and down past West Caicos. Even the distant sites off French Cay are not out of reach for these boats. Two-tank morning excursions depart at 8:45 a.m. Running times can be as short as 15 minutes to sites off Provo's Grace Bay, or as long as 80 minutes to the bottom end of West Caicos and French Cay. Afternoon and night dives are by request, as are Turtle Diver's three-tank trips to French Cay. Basically an all-day affair, these trips also include a box lunch. Turtle Divers offers a wide range of vacation packages at five different inns, hotels and resorts.