I love aquariums and this one I will have to visit next time I'm in Japan. It's located in the Churaumi Aquarium in Okinawa, Japan. It's so big that they call this aquarium/tank the Kuroshio Sea.
How Big? How about FOUR whale sharks. FOUR!!!! Not only just whale sharks, there's a lot of other types of fish such as manta rays, tunas that total about 80 species combined. Amazing. To add to the amazement, only 3 tanks in the world are able to hold whale sharks and this one can hold 4.
The thing I like is instead of just throwing in a bunch of fishes that look good (hmmm..sounds familiar), they gathered up local fishes in the area so you know they'll all get along for the most part. Very smart of them to do that.
Here's a youtube video of the aquarium. There's an HD version of it. Watch that if you can. It's pretty amazing. You know what would be awesome..if I could make this HD video into a screensaver.