While we were in Fort Lauderdale, we went on a glass bottom boat. This was a great experience.
The boat takes off on of the marinas in on the Intracoastal, and heads out to the ocean. The captain told us all about the houses (read: BIG SUPERB HOUSES with private yachts . . .) built on the Intracoastal, and was full of stories and anecdotes.
After we got a couple of mile out in the ocean, we went snorkeling around the boat. We took a smaller boat, so there was just a small number of people in the water with us, and plenty of space to swim around.
After almost an hour and a half of snorkeling, we returned to the marina. I was delighted with my experience, but a little disappointed because we had a limited area of coral that we could explore. It was too deep to see in detail, so we had to really swim down to see the colors and the fish.