If you book your cave tubing through X-Stream you can go with your 10 year old. I booked through them and my son is 10. No problem. Can't tell how it is because we don't cruise until April but all reviews have been great.
We are doing the Xstream cave tubing tour in Belize
In Costa Maya we are going to the little village of Majahual and taking some school supplies to the school and then maybe doing a snorkeling tour or hitting the beach to relax!