Just got off the July 6th western... and we went diving in both Grand Cayman and Cozumel. I would have to say I liked Cozumel better... the boat had more room in Grand Cayman, but the diving in Cozumel was a lot better....plus it lasted longer.
In Grand Cayman, the first dive is instructor led, and the second dive is a buddy dive. In Cozumel, both dives are instructor led and the reefs are a lot more colorful, and you see a lot more fish.
If you parents do decide to dive in Cozumel, make sure they purchase the video the people put on. It was very nicely done, and it even included mine and my brother's names in the beginning. It was a great souvenier to purchase.
hope this helps!
