Well in Cancun  they can take you on some nice 32 foot dives (if you
take a shovel, the water is 28 feet deep) . If you don't want to go to
Cozmel, go to Playa Del Carmen to the abyss divers they dive off Playa
no great reefs but some interesting drift dives on the Playa side

If time's an issue for you don't hesitate to catch a morning boat out
to the reefs at Cancun. It's relatively easy diving although in
January (my only experience) there's often a brisk current running.
Generally the ops are able to read it right and drop you in at the
right end for a nice easy ride. The dives aren't deep (50-60') unless
you want to do the minesweepers. Then it's only 75-85'.

If you go over towards the island it's about 40-45' max but I think
some of the coral is nicer than the deeper reefs. If you like lots of
stingrays there's a spot called Chitales just off the point that has a
lot of big stingrays.. Max depth will only be 25' but it's a pretty
dive anyway.

Again, my only experience is January and the port is often closed
because of wind and high seas, but if you can get out the diving is
decent for a nice relaxing day. If you want deeper dives with
impressive coral, make the trip to Coz. It's relatively easy to
organize a package deal right from your resort. Another option is to
go south to the ferry jumpoff point at Puerto Aventuras and try cavern
diving. Not a good choice if you're claustrophobic, but memorable if
you're not. Again, easily arranged through your resort. If you want to
organize your own cavern trip I have a name for you to contact. He
won't lose you underground.  8)

JF

Don't Get Stuck On Stupid

Is there any half decent diving near Cancun or should I just forget
about
diving there and take the two hours to get to Cozumel?

   That would depend on your idea of decent. If you're from Ohio and
your only choices are quarrys and Lake Erie I'd say yes, the diving is
decent. The drift dives are fun but nothing like Cozumel. Take the 2
hour trip.