There's a peace to swimming amongst sea life, and I felt more relaxed in the aquarium than I did in the pool. Phased by the creatures, I was able to stop worrying about breathing underwater and just "be."
Despite what you see on TV during Shark Week, diving with sharks isn't exactly rocket science. Go with a guide. Show these creatures some respect. And don't dress up like their food, and everything should go fine.
While Discovery Channel might have you afraid to ever go in the water again -- or perhaps aching to get face-to-face with sharks -- Sport Diver magazine has a quick primer on these sea critters that you should study before dipping a toy in the water.