We went to Xcaret 6 years ago on a RCCL excursion - DH, me, DS12, and DD6 (and our first cruise). We have been on 6 subsequent cruises, and I'd say Xcaret still ranks one of the best cruise days we've had to date!!! I'd highly recommend it - and go with a cruise-sponsored trip, as it was a bit complicated transferring to and from. The underground river was really fun and different. There are places where it opens up with natural light, and there are a few electric lights inbetween. I will say my DD was holding onto me for dear life - but she loved it!! This is only one aspect of this wonderful place. There are gorgeous natural pools on the edges of the ocean to swim and snorkel in, and lots of paths to explore. My son did the dolphin swim - at the time, we just signed up on arrival (not sure if this has changed). This experience was really worth it!! I remember we had to leave by 3:00. We could definitely have stayed longer, but would never trade the time we did have there. Go for it!!!!