We are going in March 2013 on Carnival Liberty, anyone in a wheelchair have advise for us? Would like to snorkel in St. John, but not sure how we would get there with the chair (my husband doesn't walk at all but swims well!) Ports of call- SanJuan, Castaway Cay, St. Thomas and Nassau. Any suggestions sight seeing tips for these ports of call via wheelchair would be greatly appreciated!