<http://www.captainmarvins.com/>
It is Capt Marvins policy (as mentioned above) to not charge you until you get there, and if your ship has to skip the port, they still will NOT charge your card for not showing up. They understand these situations. But if you choose another company, make sure you ask in an email so that you get a written response back. There are several reputable companies now.... use a search engine and look up Grand Cayman travel or vacation information .... or look specifically for Captain Bryans (or Brians?), NativeWay, Sotos... theres a bunch. Sounds like just about everyone is happy with their tours.