The ship will not wait for passengers who take privately-arranged tours and come back late. Film is sold in the duty-free shops on board. In most all of the islands Snorkeling and Diving is very popular. Snorkel and Dive gear are available for rental with the tours through the Shore Excursion desk on board. You may want to bring your own from home, especially if your skipping the ships tours and are sightseeing on your own the adventurous way.
Credit cards are the most convenient method of purchasing items both on and off the ships.
Traveler's checks can be cashed at the pursers desk on most ships 24 hours a day. Many ships also have ATM's right on board. Tip Room Service accordingly as you use it. Recommended tipping guide lines can be found in the back of any cruise brochure, but are also conveniently listed within info booklets located in your cabin. Amounts differ based according to the Cruise Line you travel on.