I just returned from a family vacation in Bermuda. One of the things we did there was Helmet Diving. You're in about 10 feet or so of water with a large helmet over your head with an oxygen line. Think about turning a glass upside down and putting it in water. Your head stays dry the whole time, you can wear glasses, contacts, whatever. You can even reach your hand under the helmet to scratch your face if need be. We got to see, feed, touch, and lern about many fish/sea creatures. Just thought I'd share a few pictures of myself, my wife, and my son - this is a true Fishlorian vacation activity!
You walk down the ladder until the water is about chest high, then they place it on your head. It weighs about 40 lbs but is padded at your shoulders. Helps keep you down under water but you don't notice the weight. We jumped up and down from the ocean floor and you can get a little bit of height before you float back down again.