Scuba diving is the only socially acceptable way to find hidden treasure, befriend a nautical skeleton, or strap a huge tank to yourself. Explore the possibilities with today's Groupon: for $34, you get your choice of a discover scuba, snorkeling, or dive-refresher course at Frogg Pond Dive, a PADI five-star dive center in Highland Park (a $69 value). The discover scuba and snorkeling classes are open to anyone, but the dive refresher course is only open to divers who have already earned their certification; it requires an additional booking fee of $21.

Frogg Pond Dive is the home of Chicago Diving Schools, who introduce the gill-deprived to underwater exploration. Students new to sea can get flippered feet wet in the discover scuba class, wherein a PADI certified instructor teaches the basics of sea breathing from the safe, never-electric-eel-filled confines of a pool. For swimmers not ready to take the plunge to the bottom of the un-briny depths, there's the snorkeling class. And divers who have already completed a scuba certification program, but are out of practice or have recently had their memories erased by Secret Service agents, can regain their aquatic adeptness by enrolling in the dive refresher.

Classes take place at the Highland Park High School pool and are kept to a size of eight students to ensure every diver has the personalized attention he or she needs. The pool is available Sundays from 4:30–9:30 p.m., and guests must call to schedule their appointment.