Cozumel and Grand Cayman over Christmas - thermal protection?

[BluewaterRocket]

I've done some diving on cruise trips in Cozumel and Grand Cayman, both in late spring and summer. I'm taking the family on a cruise over Christmas with stops at both of these ports.The whole family is certified and wants to go diving. What are water temps like in Cozumel and Grand Cayman during end of December? How much, if any thermal protection is recommended?

Thanks

 

[Mike]

Coz - unless you get cold easily a 3 mil shorty is common, water will be just under 80 degrees. Coming in on a cruise ship will limit you to the closer to shore shallower dives anyways.