It doesn't matter if you're raising the next Jacques Cousteau or your child doesn't know the difference between a snail and a squid -- a birthday party at an aquarium is a guaranteed great time. Children love aquariums because sea life is pretty weird. There's nothing on Earth quite like a sea horse but a sea horse, and unless your little one is a proficient scuba diver, there's nowhere else he can get so close to the strange, exotic creatures of the deep.
Best of all, you won't have to deep-six your bank account to finance your child's undersea extravaganza. Many aquariums have special party rooms, and if you're having an especially large gathering, some venues, such as the Georgia Aquarium in Atlanta, have large areas available that include unique views of an exhibit. You can also request a special behind-the-scenes tour, and if you ask nicely (and pay more), divers may be persuaded to hold up a "Happy Birthday" sign during a feeding!