Moon Palace is a bit out of the way for the Cancun dive ops but I'm
pretty sure I heard there was an op had set up shop there at the
resort. Also check out Puerto Morelos which isn't too far away and has
a few dive ops.

There are a number of reef sites but little to distinguish them from
one another. In between the beach and Isla Mujeres there are some
shallower reef structures with lots of fish. Off the point at the
north end of the Hotel Zone there are deeper (55-65') reefs with lots
of fish and a bit of current. That's also where you'll find the two
mine sweepers that make kind of interesting dives. There's a bit of
reef just off Moon Palace but the one time we tried it it was very
shallow and very silty so we never went back.

Check out the day trips to the Puerto Aventuras area for cavern diving
or to Cozumel for reef diving. You can probably book them through the
front desk at the resort or more likely there'll be a Thomas Moore
shop at the resort. You ride air conditioned coaches and they provide
lunch. The last time we did a day trip to Coz we stepped off the ferry
right onto the dive boat.

JF