Flower Garden Banks National Marine Sanctuary, Texas

Rule No. 1 when diving the Flower Garden Banks National Marine Sanctuary: No matter how captivating the hard corals and reef fish are, keep an eye on the open water, or you might miss something big. Really big.

I learned this lesson, as most divers do, through experience. I was nearing the end of a productive wide-angle photo dive at East Flower Garden Bank, one of the three distinct formations rising from the depths of the Gulf of Mexico about 100 miles due south of the Texas/Louisiana border. Like an oasis in a desert of sand, the peaks that form the sanctuary are the northernmost coral reefs on the North American continental shelf, hosting 23 species of coral and more than 170 species of fish. For most of the dive, I happily shot schools of chromis and creolefish, hovering over the healthy star and brain coral formations. Then, as I began to surface, I glanced up and did a double take at the silhouette of one huge fish blocking out the sun.

The fully grown whale shark — 40 feet long if he was an inch — lumbered silently through the water with its broad mouth partially open, sucking in plankton. The animal’s eyes looked ahead, seeming not to notice me as I made a beeline to get a closer look. Kicking furiously, I managed to get off a few frames before the great fish soared out of sight with just a few flicks of its massive tail.

So goes diving at the Flower Garden Banks. You just never know what you might find, and that’s what makes this place so special.

Bathed in blue-water Gulf Stream eddies, the sanctuary spans 56 square miles split into three distinct regions: the East and West Flower Garden Banks and Stetson Bank. In all, the sanctuary has a total of 17 moored dive sites that you can explore by private boat or by two- to three-day liveaboard cruises operating out of Freeport and Galveston.

The East and West Flower Garden Banks are 12 nautical miles apart. Both are topped with rolling hills of chartreuse and hazel-brown colonies of boulder star, symmetrical brain and mustard hill coral that stretch to the edge of visibility, which is normally 100 feet or more. Parrotfish, sharpnose puffers and yellowfin grouper flit through the reef, while Bermuda chub, barracuda and schooling jacks hover in mid-water. If you take the time to patrol slowly the sand patches between coral heads, you’re likely to find yellowhead jawfish, peacock flounders and sand tilefish.

The third structure, Stetson Bank, is a much smaller siltstone-based reef situated 30 miles inshore from the West Flower Garden reef. It’s a mere 700 yards long and 200 yards across, but don’t let its tiny size fool you. It’s a magnet for marine life, from sponges, fire coral, spiny oysters and arrow crabs to feather dusters and an array of invertebrates. The ten-ray star coral formation near buoy #3 is by far the largest coral formation on Stetson, and it attracts creolefish, golden morph trunkfish and scorpionfish. Unlike the other two banks, Stetson also has a wall on its north side that plunges dramatically to 180 feet.

With the nearest coral reef some 400 miles away, the Flower Garden Banks also attract large pelagic visitors like manta rays, mobula rays, loggerhead turtles and sharks. It’s quite common to see silky sharks, sandbar sharks or nurse sharks on the reefs. During the late winter and early spring, schools of eagle rays and scalloped hammerhead sharks migrate through the area, and whale shark sightings — while sporadic — are reported throughout the summer months.

Of course, the area is also famous for the annual mass coral spawning. Seven to 10 days after the August full moon, the hard corals on the East and West Flower Garden Banks simultaneously erupt, releasing BB-size sacs of eggs and sperm in what is often described as looking like a reverse snowstorm. The spawn gradually floats to the surface, forming musty mats of nascent coral polyps that will build the next generation of coral colonies.

If you’re looking for a coral reef experience with the possibility of some big animal encounters but without the hassle of security inspections and Customs forms, think about a two- or three-day adventure at the Flower Garden Banks. It’s a place that can be full of pleasant surprises.

How To Dive It

Conditions: The Flower Garden Banks have two dive seasons. The summer season is May through October, and winter diving runs from February through April. Surface water temperatures range from the low- to mid-80s°F in the summer months to the low- to high-60s°F in the winter. Visibility varies from 75 to 125 feet in the summer to 30 to 75 feet in the winter months. Currents and surface conditions can be unpredictable this far out in the Gulf, making this a dive adventure best suited for intermediate and advanced divers.

Dive Profiles: Dive depths generally range from 60 to 90 feet. Nitrox is a good choice for offsetting some of the extra nitrogen loading that can occur on the deep, flat profiles. On two-day liveaboard trips, operators offer four dives during daylight hours plus one night dive on the first day; two morning dives on the second. As a safety measure, divers are also limited to a maximum depth of 130 feet on the first dive of the day and 100 feet on all subsequent dives. All surface intervals — without exception — are two-and-a-half hours minimum. Liveaboard crews caution divers to make slow ascents, a one-minute safety stop at half their maximum depth and a three- to five-minute stop at 15 feet.

Getting There: The sanctuary formations are located 70 to 115 miles off the coasts of Texas and Louisiana and accessible by private boat or by liveaboards operating out of Freeport and Galveston.

© Alert Diver — Q1 Winter 2010