Free for CoCo Cay is the beach. CoCoay is just a great beach day. (You must love the beach) You can rent the floating mats for $10.00 - Snokeling is about $15- $20. We have been to Coco Cay three Times and have enjoyed every time. This is a private island so everyone on the island that day will be from your ship.
On our cruise we found one little house type bar with A/c. That was a godsend because it was freakin' hot. We did swim quite a bit, but no formal type excursion. Some neat stuff to buy, got a great straw bahamas hat I will be wearing this week in gulf.
Jet Skis are always fun. I found a hammock there and read a book. Also, there is a deserted beach way around the right side past the inflated water slide, very pretty over there. Don't rent a $10 float until you get there, I rented one and it was too cold/rainy once and they wouldn't give you a refund, what a rook!