Oh, for sure, we know that very well, that the ship doesn't wait for you!! We've been on over 30 cruises ourselves, most in the Caribbean, and have taken some pretty hare-brained excursions on our own, that I probably wouldn't do now. These days I probably wouldn't take the ferry on my own from St. Maarten to ST. Barts, or DELIBERATELY be left behind on Isla Mujeras, to make our way back to Cancun, or leave our cruise ship in St. Thomas to fly to St. Maarten, and spend the night there, to (hopefully!!) meet the ship when it arrived the next day in St. Maarten. But we always made sure we had a credit card and our passports. Doing things on your own involves a level of personal responsibility that some prefer not to take.