iScream I think you were considering DWM, right? There is a shallow area by their shop in front of Señor Frogs where they will let you get in the water to check out equipment. I think they charge $5 or $10 a tank, or they might waive it if you book a package with them. I've done that before when I've wanted to test new stuff, but it might depend on whether there is a cruise ship nearby at the time. I can't quite remember the details. If you email their contact person Paddi I'm sure she'd be able to confirm whether this is still a possibility.
From what I've read here other shops often offer something similar. HTH!
From what I've read here other shops often offer something similar. HTH!