i came across this underwater camera (non-disposable, mind you) in one of the stores down there. it was actually the only one in town, so we felt lucky to have gotten one at all after the apparent mexico beach underwater camera rush of '06.
this portion of beach was obviously not used by humans very much because the fish were everywhere. it was a little scary at times because there were so many of them everywhere. i think i saw a sting ray and i'm pretty sure i kicked a crab. this little guy below wouldn't leave me alone. so i took a picture of him... with my UNDERWATER CAMERA!
(now, this is a pretty simple camera, focus free, no zoom, so as you can see these fish are right up in there. course, i think those are tiny fish, so they arent so bad.)
it was some mighty clear water. however, on the 2nd day it was a bit darker outside so i could only see about 5' in front of me under water. this scared me. had something come out of the watery shadows, i would've crapped myself. so i did less underwatering that day and more sand castling.
i do recommend mexico beach though. it was a very relaxing place.