South Padre Island, Texas

If it weren't for its big eyes, I'd never have noticed the scorpionfish camouflaged against the dense mat of macrobiology that covered the steel supports of a toppled rig structure off Texas' South Padre Island. Scorpionfish are mottled-brown and have ugly, leafy skin flaps that make them look like nondescript, algae-encrusted rocks.

The good news about scorpionfish is they are not very aggressive. They normally just lie around like they're in some kind of trance. But the not-so-good news is that they have sharp, venomous dorsal spines and are masterfully inconspicuous. Luckily, scorpionfish aren't much more of a threat to divers than are sea urchins. I was taking a get-in-your-face approach, looking for close-up photo subjects on a less-than-usual-viz day. Even though runoff from recent flooding had reduced the park's visibility to less than 25 feet/8 m, it didn't take long to find the first one, and then a second. Before I knew it I was spotting scorpionfish in pairs, and even discovered a family of three.

The Padre Island Underwater Park, also called "The Artificial Reef," is part of the Texas Parks and Wildlife Department's Rigs to Reef Program.

It's located just off South Padre Island, a thin barrier island at the Texas/Mexican border. Besides the plenteous population of spotted scorpionfish, I also found numerous tiny tuscalated blennies hiding out in barnacle shells, gatherings of arrow crabs, a medley of reef tropicals and loads of game fish. A second rig jacket and a nearby ocean tugboat sunk in 72 feet/22 m of water complements the Park, which is situated 7.2 miles/11.6 km off the South Padre jetties. The 60-foot-/18-m-long tug sits upright on the bottom, and features two wheelhouses and an engine room to explore. The newest addition to the park is a 150-foot-/46-m-long Navy repair barge complete with anchor and chain. It was sunk on its side last August about a hundred yards east of the tugboat.

South Padre dive operators use the underwater park to train divers from entry-level Open Water to specialty courses. According to American Diving's Tim O'Leary, the barge is an excellent training site because the top of its long, flat deck is at a depth of only 40 feet/12 m. Operators set up drift and tag lines that connect to the down lines in a fashion which allows divers to make descents to the barge and return to the boat without ever leaving the lines. O'Leary even uses the barge for some of his rebreather course dives, and entry-level wreck training dives are made on the park's tugboat. The Scuba Shack uses the park to certify teenagers from the Laguna Madre Boy Scout Camp. Owner John McIntyre certified 100 scouts there last summer.

The steel framework of South Padre's offshore rigs forms a sanctuary for an entire food chain of inhabitants, from tiny hydroids, barnacles, anemones and other clinging creatures to schools of majestic spadefish and groups of silvery lookdowns. The latter flutter through the water column, appearing almost angelic with their long, very fine dorsal filaments. But there is no church choir in the balcony. Instead, diesel-powered generators resonate overhead in a bass hum.

Eight large platforms are scattered in an area 42 miles/68 km north of the South Padre jetties in depths of 150 to 220 feet/46 to 67 m. Exceptional summer visibility and the multitudes of fish make the 4:30 a.m. departure worth it. Little Adam, a popular platform in this area, hosts hordes of tropicals like angelfish, cocoa damselfish and butterflyfish. Larger possibilities include jewfish, tarpon, spinner dolphins and even whale sharks. Scuba Shack's McIntyre explains that the iron islands are used for advanced dive training because of the deeper depths.

Seven and One-Half Fathom Reef, one of the Gulf's few natural reef formations, is an altogether different experience. This site is located just north of Port Mansfield, about 2 miles/3 km off the deserted beach that's protected by the State Park program. The reef was a watering hole for camels, mammoth and mastodons 10,000 years ago. Today ridges, gullies and rough, rocky overhangs make it a magnet for a diversity of extraordinary marine life such as purple-mouth morays, sea horses and toadfish. Other residents include grouper, amberjack, snapper and barracuda. Divers have also discovered mammoth teeth, bones and different fascinating fossils on the reeftop.

If I told you there was another site where three 400-foot-/122-m-long ships lay at a depth of 100 feet/30 m, you'd probably wonder what event caused such a disaster. The fact is, the ships were intentionally sunk in the 1970s by the federal government as part of the Liberty Ship Program. Designed to enhance the fish population in the Gulf, nine Rigs to Reef structures were added to complete the complex. It's located about 2.5 hours north of South Padre Island and now known as the Port Mansfield Liberty Ship Reef. The ships are upright, and their tops reach a depth of 85 feet/26 m. Some of the gas and oil structures, which were donated by petroleum companies, top out at 50 feet/15 m. Operators run advanced wreck training that can include penetration dives on the Liberty Ships.

South Padre Island touts some of the finest beaches in the entire Gulf of Mexico. Add a seaside lineup of condos and luxury hotels, a great choice of eateries, a Central Florida-like climate and spectacular sunsets, and you'll understand the attraction. South Padre draws a diverse crowd, from the spring-break college revelers to the more senior snowbirds and retirees. Boardsailers and fishermen alike claim the Laguna Madre is one of the best recreational bodies of water found anywhere in the Lone Star State.

Be sure to visit Sea Turtle Inc., founded by the longtime resident "Turtle Lady" Ila Loetscher. Volunteers offer "Meet the Turtle" presentations twice a week. You'll see leatherbacks, hawksbills and the highly endangered Kemp's Ridley turtles.

Summer water temperatures reach the mid-80s F (27 C) but it's not uncommon to encounter 5 F (3 C) thermoclines at depth. Winter gulf temperatures dip to the low 60s F (16 C). Count on the best visibility during the prime-time months of July through September, when the Gulf Stream sends eddies of clear-blue water close to shore. The dive season runs from March through October, but the best diving is from June to September.

A 2-mile-/3-km-long causeway connects South Padre to Port Isabel on the mainland. Nearby airports are in Brownsville (30 miles/48 km) and Harlingen (45 miles/72 km). In less than a 30-minute drive south, visitors can enjoy the much-renowned Gladys Porter Zoo, or cross the border to Matamoras, Mexico, and experience its cultural attractions, tasty restaurants and bargain shopping. Two nearby medical facilities have recompression chambers and trained staffs who can handle diving emergencies.