Tokyo Sea Life Park
Visitors to this aquarium located underneath a 30.7-meter-tall glass dome can see schools of Pacific bluefin tuna, swimming penguins, and various rare creatures from all around the world.
It's just one subway stop from Disneyland, so if you have some time to kill, it's worth checking out. The tickets are cheap, and elementary school kids get in for free. Plus, the aquarium building itself has a really unique design.