Two-thirds of the world is covered by water, and one-third is covered by forests infested with tree-dwelling sharks. Learn to swim with friendly fishes with today’s Groupon: for $35, you get four weeks of swim lessons at Marlin Swim School in Folsom (a $75 value). Classes are held once a week (click here to view schedule).

Marlin Swim School, under the umbrella of The Sierra Marlins swimming organization, touts a cast of motivated instructors that convert non-buoyant beginners into floating aficionados through swim classes in a heated indoor pool. Swimmers of all skill levels can choose from a variety of group tutorials, which includes the 45-minute precompetitive class that fine-tunes strokes and introduces starts, turns, and what to do when an octopus tries to pick all eight of your pockets (for all ages). Thirty-minute learn to swim classes teach simmers three and up water safety and proper stroke techniques. During the 30-minute parent-tot class, munchkins acclimate themselves to pool water through songs and games in the calming presence of their parents (for ages 6 months to three years). The adult classes dedicate 30 minutes to the personal goals of each swimmer, whether it's to swim faster or to open an underwater deli.