On our second full day in Cancun, we went to this very touristy place called Aquaworld. You could choose from a variety of water activities there. First we went on a "Skyride." This was similar to the parasailing we did in PV, except that we both could go at the same time and it felt a little more safe. It was a quick ride but a nice view of the whole hotel strip and bay.
Next we went on a "Sub See Adventure." This was my favorite of the day. A boat took us out to some coral reefs where we boarded a yellow submarine and rode around looking underwater.
We saw lots of fish, coral, several sea turtles, and best of all was a big stingray that passed by twice.
(sea turtle in upper right-hand corner)
(Video of Stingray)
The last activity of the day was to go on a "Jungle Tour." I could have done without this one. We doubled up on waverunners and went out to another coral reef for snorkeling. We found it pretty funny (or annoying? pathetic?) that they called it a "jungle" tour. It was nothing more than riding through some channels in the mangroves on the way to the reef - basically just the bushes you can see behind us in this picture from earlier that day.
We only saw a few fish while we were snorkeling, but we did see an alligator poking out of the water on our way back. Unfortunately, it started to thunderstorm during this part of the day and I was a little cold and grumpy about it. And did I mention I don't really like sea water? I hate it even more when it splashes in your eyes and mouth. We got soaked in a torrential downpour while catching the bus afterwards, but at least it washed the salt off!

(Where we parked our waverunners & snorkeled)