If Kevin Costner's prediction comes to fruition on September 17, 2010, mankind will be forced to undergo lengthy plastic surgeries adding webbed feet and chest gills. Avoid bodily alteration by prepping for the aqueous future with today’s Groupon: for $20, you'll get a Try Scuba Class at Louisville Dive Center (a $40 value). Open to ages 10 and up, today's Groupon also makes for a superb gift for the H2O-curious father.

The Try Scuba class is a safe, simple way to figure out the fundamentals of marine missioning, which the passionate underwater voyagers at Louisville Dive Center have been teaching for more than 30 years. After each student displays a medical history form, towel, and swimsuit, a friendly, certified instructor will lead the class to the shallow, warm pool, where students will learn the basic tenets of underwater breathing before being allowed to plunge into the artificial pond for the duration of the session. While submerged, divers can play Frisbee and snap underwater photos of friends reenacting World War II battles in slow-motion under the sea. If goggled visions of high-fouring manatees on the open water waltz in your head, Louisville Dive Center will happily apply a $20 discount for scuba-certification classes. In addition to gaining scuba knowledge, you can gain scuba gear by presenting your Groupon at Louisville Dive Center's gear shop for 10% off a wide selection of pinnacle manufacturers like Scubapro, Oceanic, Aeris, Genesis and Sherwood.

Call ahead to schedule the class.