Few, if any, places in U.S. waters offer divers regular encounters with whale sharks and giant manta rays, but you can do just that at the Flower Garden Banks National Marine Sanctuary in the Gulf of Mexico. About 110 miles off the coasts of Texas and Louisiana, these are the northernmost American coral reef ecosystems, and because of their remote location, they are among the healthiest in the world. NOAA recognized the banks as unique underwater resources, and created the 56-square-mile sanctuary in 1992 to protect the banks from anchoring and prevalent offshore oil and natural gas drilling.
The Flower Garden Banks actually comprise three separate regions: the East Flower Garden Banks, Stetson Bank and the West Flower Garden Banks. Fishermen discovered them in the late 1800s and named them after the brightly colored sponges and invertebrates they sometimes pulled out of the water.
Today, experienced divers can swim with whale sharks and mantas, get up close and personal with schools of hammerhead sharks and glide among coral heads the size of Volkswagen Beetles at any of the three banks. The best time to see the whale sharks and mantas is during the summer months, and hammerhead season is from February to April. At once beautiful and wild, the sanctuary is also known for a unique annual occurrence. Each August, about a week after the first full moon, divers can witness a coral spawning where billions of tiny coral polyps release eggs and sperm into the water in an event akin to an underwater fireworks display. And if you're lucky, whale sharks may show up to feed on the gametes.
About a three- to eight-hour boat ride depending on your departure point: Three hours from Galveston, Texas, and roughly eight hours from Freeport, Texas. Gulf Diving, LLC operates two live-aboards out of Freeport ($440- $535 p.p.), and Fish-N-Divers departs from Galveston at a cost of $500 p.p.
Experience needed: Intermediate to advanced.
Where: 110 miles off Galveston, Texas.
Conditions: Unpredictable currents. Water temps range from 60 to 80 degrees. Typical dive depths, 60 to 110 feet.
When: Year-round, but conditions are best from June to October.