Wonderful, interesting excursion to fascinating ruins. We took the adults only tour. Highly recommend it. The ruins range from being excavated to being in the condition of being covered with vegetation. Good worthwhile tour. It was hot hot hot and busy, but well worth it. We felt somewhat obligated to buy something from the vendors - we know that they depend on the tourist trade for sustenance - but they are a bit pricey even after negotiation. Just be aware that you will probably not get a bargain here and check it off to providing some help to a very poor population.
My children loved their excursion to the dolphin swim, but we did not go on that, so I can't comment personally. We did shop here. Be aware that you exit the ship and walk a gauntlet of shops with people out trying to get you to come in. Choose carefully and do comparison shopping. We saw chess sets in several stores - the first wanted $40, the second asked $100 for the very same set. A couple coming into the store right behind us was told $45 for the same set from another salesman. Just be careful and buy only what you want. I found a pair of earrings that I fell in love with. The salesman asked $60. When I said no, he asked what I was willing to pay for it. I said $25 - and that truly was all I was willing to pay. That's what I got it for. I really don't think it was worth any more than that.
We did buy a small diamond anniversary band from DI (Diamonds International) - they were in every port. I don't know if the prices were good or bad - I just saw what I wanted and we were able to negotiate a bit of a reduction. I know the diamonds are not the best, I went there with my eyes wide open and I got exactly what I wanted. I am not a shopper and I don't see this as an investment. I just wanted this band to wear as a token of our 40 years together and my husband was happy to do it. Look carefully at the merchandise because quality is spotty.
Castaway Cay is a delightful island. I didn't know how it was going to absorb 2700 people plus staff and it was crowded but that didn't stop it from being an absolutely delightful place to be. We had heard it was going to be crowded so we left as soon as we were able and we found several lounges under an umbrella between two palms that kept us delightfully comfortable all day. The beach became completely full, though there was a nice wide fairly empty stretch of sun and beach leading up to the beautiful Caribbean lagoon. There are two family beaches and one adults only beach. I did not see that, so I can't judge that. But one family beach has a snorkeling bay and the other has a water slide. This water slide doesn't compare with the one on the ship - my grandson went several times but he liked the other one on the ship better. There are loads of things to do on the island and I am sorry I did not rent a bike to see more of the island. That's the only thing I regret. But I wanted to hang out with my kids and that's what I did. It was a wonderful beach day. You can rent floats, snorkel equipment, bikes, jet skis - all sorts of adventures can be had. But I love being with my family doing nothing special, so that is what I opted for. We did go to see crab races and my husband took the older boys to the InDaShade area where he played giant chess with one and giant checkers with the other. They had a great time. My son and son in law took a snorkeling excursion which my son said was not as good as the St. John ones we went on but for my son in law, it was his first experience and he loved it. My husband rented snorkeling gear and just cruised off the beach - he loved it. Food is provided but not the high point.