If foam noodles can be found floating on the surface of almost every pool, think how many perfectly salted meatballs must be at the bottom of the ocean. Discover the sea's sunken treats with today's Groupon: for $149, you get a PADI open-water diver-certification class at International Scuba in Carrollton (a $329 value). Students should have their own mask, fins, snorkel, and boots (available at a 10% discount from the onsite shop), but International Scuba will provide all other equipment and course materials.

International Scuba's PADI-certified crew of submarine-impersonating instructors offer open-water diver-certification classes that get students sea legal within days. Before beginning class, students should pick up the educational materials and brush up on basic cephalopod-communication skills. After three or four small-group confined-water sessions—held on weekday evenings or weekends—students venture to natural bodies of water for four checkout dives in their adopted aquatic habitat. Depending on the season and the student's desires, the open-water excursions can take place as near as the Clear Springs Scuba Park in Terrell or as far away as the Caribbean, should divers opt to join any of the center's tropical dive trips. Scuba-park entrance fees ($10–$30) are not included and vary by location, as does the likelihood of encountering shipwrecks packed with pirate ghosts.