More than 70 percent of the earth's surface is covered in water, which fails to explain why the remaining 30 percent contains 100 more aquariums than the moon. Sop up a lunar ocean of experience with today's deal: for $20 you get two general admission tickets and a souvenir guidebook at Sea Life Arizona Aquarium in Tempe (up to a $41 value). This Groupon expires on September 11.

For those humans who are lamentably landlocked, Sea Life Arizona Aquarium offers a hands-on, educational aquatic experience filled with up-close animal viewings, fishy feeding frenzies, and interactive encounters. Seafaring adventure awaits across the multifaceted aquarium map, which charts a knowledge-saturated journey through 26,000 square feet of saltwater and freshwater chambers that house more than 5,000 aqua-inhalers, ranging from sharks to stingrays to green-tentacled octopus gardeners. Patrons can embrace full liquid immersion while staying dry in the walk-through ocean tunnel, whose transparent walls give visitors a 360-degree view of the marine world around them. Back above the surface, tactile learners can dip their paws into special touch tanks to interact with tidal denizens and discover the proper way to shake hands with a starfish.

Aquarium-goers can soak up the latest ocean gossip at daily talk and feeding times, including shark, stingray, and seahorse feedings, and discover how to help guard aquatic abodes with afternoon conservation talks. The interactive, five-tank Claws exhibit also showcases the world’s largest species of crabs, whose fearsome pincers can crush coconuts, but only to make piña coladas for their friends.