Pick 4: St. Croix, St. Kitts, Dominica, Grenada, St. Thomas

[Kryssa]

I'm going on a family cruise next year and we are stopping on these 5 islands:

St. Croix
St. Kitts
Dominica
Grenada
St. Thomas

At one of the stops we will do a family activity together. Unfortunately, 2 of my family members get really seasick on small boats, so it will be something land-based.

Which of those locations has diving you'd be most willing to skip?

Thanks for your help!