Poseidon Adventures Limited, Tulsa

The master scuba instructors at Poseidon Adventures Limited have been helping students earn their gills for more than 30 years. The all-inclusive scuba center boasts a heated indoor training pool where they provide PADI-certification classes every day of the week. What's more, the schedule features 35 classes that cater to beginners and advanced divers alike, with specialty courses that cover topics ranging from night diving to navigation and underwater photography.