My son was at a wedding here in 2010 and although some of the party did use the gym he didn't go so he doesn't know how good it is.

He said it was a fantastic hotel though and the photos he's got are fab!

Hi , we stayed at the Caribe 3 years ago and the gym was good. Here are some pictures from the net

http://www.cancunpictures.net/albums/userpics/10066/riu-caribe-gym.jpg

http://www.sunseekersvacations.com/photos/riu-caribe/BVkRg4KQu9SSmMC98z4ZUH0cd4n7s5nX/riu-caribe-gym_800.jpg

http://photos.hotelsclick.com/ME/CUN/20035/14.jpg

As for your booking question on the other thread I would say the reason no flights come up is because you are trying to book to far in advance, we came across this problem when helping some friends to book a holiday there.

The Caribe is a great hotel as are all the Riu properties in Cancun, but the Caribe has the best beach by far.

Hope this helps