Splash Aquatics also features freshwater items, decorative elements for your landscape, and much, much more. A theater is on the grounds and you can relax with some freshwater fishing (not 7Seas Fishing, but an original game that is rather fun). If you'd rather not dive in with the fishies, the aquarium has a tunnel tour for landlubbers.
For divers, snorkelers, beach lovers, and anyone who just likes exploring, Kaikou has also built Dive World: PADI Scuba Diving Underwater World (SLurl). Usra and I dive there a lot. Like the aquarium there is a lot to see and much to learn. Educational signs at Dive World link to highly-informative Web pages. Really, you don't need dive gear or to be a mermaid or even have a swim AO*). You can simply walk the ocean floor (or fake swim in Fly mode).
*Swim AO: Usra uses the Zi Ree's ZiSwim (SLurl? Shop is missing!) while I use the Swimmer by Siggy Romulus (SLurl). Many AO attachments allow you to add animations for swimming, but don't actually keep your avie afloat like these specialty units.