I agree with 2vets. If you dive often in the Caribbean or other similar place, you might find it tame and cold. DH and I did it last Oct and enjoyed it. But I don't think I would do again. When we did it The Living Seas was closed and only the restaurant was open. So that may have taken some of the atmosphere away.
They do have showers and lockers to store your stuff. The locker rooms have hair dryers, soap, shampoo, and towels. They provide the equipment, but you can bring your own mask (if you want). They make a DVD and you can purchase it after the dive. After the dive you change and shower and then watch the DVD (and purchase it if you want), get a certificate and t-shirt.
HTH,
Ginger