my shout, 'under rated'
cancun is very over shadowed by its neighbour cozumel, rightly so but cancun also offers good diving.
with over 18 dive sites around, wrecks and reefs there is plenty to see and do! eagle rays are all over the wreck dives and the reefs are full of nurse sharks, green eels, turtles, barracuda all the fish you spot on a fish id chart, occasionaly we see balck tips too.
viz averages 80ft, a good day is 100ft+ and water temp is currently 81f, no more than 20 mins boat ride to the sites, easy and convienient.
cancun does have big ops, try and avoid those ones as you ll be herded onto the dive boat, taken to a crappy site and given two 35 mins dive as they have another boat load waiting at the dock!
not trying to plug my own op here but we offer hotel pick ups and the most personal attention in cancun, check out
www.mayanaquadive.com if your heading this way!