I've been to Punta Cana many times but I can't seem to find it once I'm
there.  Most people refer to Punta Cana as the airport or the numerous beach
resorts easily accessible via a short drive after arriving at the airport.
With that in mind, you should check with the resort at which you have
reservations as to availability of diving on site.  Most of the resorts have
their own dive shop or pony with nearby properties.  They will arrange
diving.

How is the diving?  It's not great.  There was hurricane damage and sand on
the coral.  The reefs are not in good shape from exploitation of marine life
and lack of care on the part of those using the resource.  You won't have to
venture very far to find a divemaster willing to stand on the coral, anchor
in the coral, or take something that looks good.  Many operators arrange
dive trips south and west to the marine park.  The diving is better there.
That is a day trip.  There is also limited cave diving not too distant.  I
haven't done the caves - didn't even know about them until I saw a program
on TV a year or so ago.  The last few times I've gone to the DR I didn't
bring my dive gear.

Another thing that torques my grape is the airport security when I was
leaving the country.  They let me keep the batteries in the flash, the
camera battery, and the spare camera battery.  (The camera batteries are the
kind that only work in the camera.)  But it was just too dangerous to let me
back on the plane with two new 4 packs of double A batteries.  Hey, maybe
they were right - the plane made it safely.  And somebody's kids had fresh
new batteries for their toys.

Remember to wait 12-24 hours before flying after diving.  Check the DAN
web site (http://www.diversalertnetwork.org/) for the details.