Breathing underwater, like eating fireworks, constructing a monument, and getting married, should only be attempted if you're confident you can do it. Today's Groupon to Surface Interval Scuba in Arlington gives you all the skills you need to mingle with the mermaids. Choose from the following options:

• For $20, you get a Discover Scuba experience for one (a $50 value).
• For $38, you get a Discover Scuba experience for two (a $100 value).
• For $129, you get scuba-certification course and gear rental (a $299.95 value).

Discover Scuba classes occur two Sundays per month between 8 a.m. and 1 p.m. at either Kirby Creek Natatorium or McFalls Pool, but Groupon purchasers need to visit Surface Interval Scuba’s store location in Arlington ahead of time to fill out a waiver and be sized for equipment.

A cadre of PADI-certified instructors guides students through a cornucopia of classes, filling noggins with the know-how required for scuba-diving excursions. Greenhorned divers can sample the thrill of underwater respiration in SI Scuba's Discover Scuba program, designed for beginners. Over the course of an hour, students will learn the ins and outs of oxygen-tank and regulator operation as well as basic safety rules from the comfortable and controlled environs of a giant, squid-free swimming pool.

Those champing at the bit to tread into Neptune-governed waters can get certified in the Open Water Diver certification course. Over the course of three–four days, students will receive 12–16 hours of combined classroom and pool-bound training before taking to one of the specialty open-water areas (a $30 admission fee applies to diving at Clear Springs Scuba Park in Terrell and Athens Scuba Park in Athens). Outfitted in the swankiest of scuba gear rented from SI Scuba, aquanauts will increase their diving limits up to 100 feet and hone in on navigation skills while improving their chances of finding work repairing underwater cell-phone towers.