I’m generally not into aquariums and zoos, but I was really impressed by the Georgia Aquarium. It’s the world’s largest aquarium, and they have the world’s largest tank. You can see one angle of it in the Bioshock Bleep Bloop, and that’s the small window.

Also - for just $325 you can go scuba diving in the tank for a half-hour. Price includes equipment and certificate of participation.