The National Aquarium in Baltimore is easily my favorite aquarium of all time. The price of admission is quite steep, but it's definitely worth it! In addition to several floors of displays, there's a living rain forest, a dolphin show amphitheater, and a brand new wing. Food is quite expensive and nothing worth describing, so either eat beforehand, or grab some food after. The gift shops are fantastic, too; don't miss them. Be sure to check out the Fridays after Five special, when admission is $5; it's not all the time, though, so check the website.
more