Artificial reefs create environments for colorful marine life

During my weekend dives, Jim Mimms, dive master with Ocean Diving in Pompano Beach, put our catamaran-style dive boat on the sites as easily as if he were driving down to the corner 7-Eleven. Although all the wrecks are marked with navigational Loran coordinates and some even have mooring buoys, local dive boats are still the surest and safest way for visiting divers to reach the sites. In addition to providing air fills and Scuba rental gear, shops give you the latest info on diving visibility and currents -- which can vary widely between seasons and even days.

Mr. Mimms told me that, while summer waters are usually the calmest and the clearest for diving, most dive visitors come in the winter simply to escape the northern climate. Still, he admits "fair" diving conditions for a Floridian may mean excellent diving to a Marylander.

As our boat enters the ocean from the Hillsborough Inlet near Pompano, Mr. Mimms explains that the first natural "reef line" is just offshore in 15 feet of water, followed by a second in 45 feet and a final one in 80 feet. While visibility on the deepest reef line is the best -- and sea life is the most spectacular -- the nearest can be reached by snorkelers from the beaches. Here, tiny tropicals like fairy basslets and butterfly fish are often found in profusion.

I also learn that one of the near-shore artificial reefs is not a ship at all but a series of large concrete structures called Eurojacks, scattered in 10 to 20 feet of water just north of the Dania fishing pier. Although the "jacks" were sunk to protect the shoreline from erosion, they have become encrusted with the sort of marine growth that attracts fish -- as well as snorkelers.

As we approach the site of the Mercedes I today, Mr. Mimms advises the divers on board that although there is a strong surface current with a thick layer of visibility-obscuring plankton, both the current and the plankton will nearly disappear on the bottom.

A mate drops the anchor on what was once the captain's bridge of the ship. We all suit up with tanks, weights and other gear and enter the water by jumping single-file off the stern of the Sea Cat. While a few divers are dressed in full wet suits, the water is in the mid-80s today, and I feel comfortable wearing only swimming trunks and a T-shirt. One young woman dives in with a two-piece swimsuit under her tanks.

I pull myself hand over hand through the strong current down the anchor rope until I reach the bridge in 55 feet of water. From here, my dive buddy and I flipper down to the current-free leeward side of the wreck to start our exploration. Although visibility is sometimes so clear that the ship can be seen from the surface 97 feet away, our vision today falls off at 40 to 50 feet.

On the bottom, we swim through large holes sliced into the hull of the Mercedes I. The holes were cut to help the current circulate so as to nourish marine life down inside the two cargo bays. A light coating of algae started growing on the structure after just a few days underwater. Within six months, sponges and small hydroids covered the hull. Today, six years later, the ship is coated with soft and even some finicky hard corals. Taken wholly, the Mercedes I looks like the classic phantom shipwreck in every B-grade maritime melodrama ever made.

We flipper up and over the edge of the gunwale, dodging the stronger current, and then descend again to the crew quarters. To do this, we move weightlessly down the hallway at the edge of the deck. Thick schools of purple-striped grunts part to let us pass.

I poke my mask up against a porthole where a small, nearly transparent, cleaner shrimp flits about. Inside the cabin, another diver's light illuminates the head of a large, bright green moray. Back outside, a dozen yellow-tailed snapper flash by just over the edge of the gunwale. About 50 feet beyond them, a sea turtle churns by with a sluggish grace.

We swim the perimeter of the Mercedes I, ducking down once more to the 97-foot bottom, where I finally notice a gigantic spiny lobster hiding just under a portion of the bow. If lobster season were open, he'd be hanging over the edge of some diver's dinner platter by now.

After 40 minutes underwater, we flip back to the bridge and return to the surface via the anchor rope, saving just enough air for a five-minute decompression stop at 15 feet. I look back toward the bottom where I know the Mercedes I to be, but all I can see are ghostly shadows dancing at the edge of my visibility in the warm tropical waters.

If you go . . .

Since currents and deeper depths are a factor in artificial reef diving, certified divers should be experienced in those conditions. Some dive shops in south Florida offer wreck certification courses that focus on entering the inside of the wrecks.

Most large dive operations offer dive packages that include two dives a day (weather permitting), air fills and lodging. Rooms are harder to find and more expensive in the winter and during spring break.

For a list of dive shops and motels/hotels:

* Greater Fort Lauderdale Convention & Visitors Bureau, 500 E. Broward Blvd., Fort Lauderdale, Fla. 33301. Phone: [phone].

* Miami-Dade Convention & Tourist Bureau, 701 Brickell Ave., Suite 2700, Miami, Fla. 33131. Phone: [phone].

For more information on the Broward County (Fort Lauderdale area) reef program, including a booklet describing wreck sites: Office of Natural Resource Protection, Beach Erosion Office, 609 B First Ave., Fort Lauderdale, Fla. 33301. Phone: [phone].