We are land people so I have no suggestions as it relates to sailing.

He probably has done most things I would recommend but I will share two things we did recently that he might like.

Caribbean Helicopters out of Antigua offers tours of the volcano on Montserrat. We did this last month and it was great. The pilot was very engaging and knowledgeable. Seeing it from the area gave a completely different perspective.

Our son loved the frigate bird sanctuary on Barbuda. You need to get a guide as access to the area is regulated. I assume the tourism office (such as it is) could give you names of providers.

Also, Gumption's tour of Necker is fun if your son (and the parents) like animals. We thought it was great.