Dive into a new experience as an aquatic guest

I was kneeling under 12 feet of water when the sensation began, the feeling of something soft and velvety on the back of my neck. A minute passed, then another, and it was still there, a feathery pressure.

There were nine sharks swimming near me, but I wasn't worried about the tickle coming from one of them. They all kept a distance, even if that was barely a foot away at times.

But when I decided to reach back and brush away what I felt on my neck, dive master Yves Delpech, who was behind me, suddenly pushed my hand.

"Didn't want you to put your hand in Gill's mouth," he said after we finished the dive.

Gill is a 250-pound Goliath grouper, who finds great sport in perching on the head or shoulders of folks whose attention is on sharks. Those toothy critters are the prime attractions in the "Dive With the Sharks" program at the Florida Aquarium in downtown Tampa, but Gill also has several rows of teeth sharp enough to seize the crustaceans that are part of his diet.

The big grouper goofs with visitors as relentlessly as does the blind zebra shark, Zoe, who lives in the Wings in the Water tank of the National Aquarium in Baltimore, another of several aquariums in the country that offer the chance to pay for a dive with exotic critters.

In Baltimore, Zoe kept bumping me and rubbing against me, her abrasive skin evident despite my 3-millimeter-thick wetsuit as rays brushed their silky undersides across my head.

Baltimore and Tampa's programs and similar ones (see accompanying list) are open to certified divers, but age minimums, certification requirements and the equipment provided vary. Check the aquariums' websites for more information. Some aquariums, including Underwater Adventure at the Mall of America, have snorkeling options for swimmers.

Wealth of creatures swim by

Why dive in an aquarium when there are oceans and lakes aplenty?

Cost is far less than a trip to Hawaii or Belize or the Caymans. You can pair the dive with a trip to a major city, and your kids (if they are too young to dive) can have a ball in the aquarium and watch through "underwater" windows as their family members frolic with the fish. Also, everyone learns something about the threats facing our marine habitats.

"You would need 25 years of diving to interact with as many species as you do on these two 30-minute dives," said John Harman of Atlantic Edge Dive Center, which runs the guest diver program for the Baltimore aquarium. "We have one woman who has done this dive five times."

The circular coral reef has 60 species of fish, including some spectacularly large angels, several types of grouper, wrasses, margates, snapper and a green moray eel named Oscar. You can glide under archways, squeeze through a "cave" and swim at different levels.

The six types of rays and Zoe the zebra shark have been sharing the Wings in the Water tank with Atlantic tarpon, a blacknose shark and Calypso the green sea turtle. Calypso gets around fine despite the amputation of a flipper necessary to save her after rescue from a fishing net off New Jersey a decade ago. I got to scratch her back, which causes a similar reaction to scratching a dog's "magic spot."

In his shark-dive briefing, Tampa aquarium dive master Mike Knudsen dispelled some myths about these much-feared creatures. Shark populations are dropping worldwide because of demand for their fins (shark fin soup is an Asian delicacy), their meat, teeth and hides. They do not reproduce fast enough to keep up.

Tampa has five types of sharks, none of them "man-eaters" (Great white, tiger and bull are the only truly dangerous species, Knudsen said). Florida Aquarium officials note that divers have completed 49,500 dives with zero shark incidents.