Dunn's River Falls does have lockers for a fee. I would not bring anymore cash than you plan on spending or can afford to lose, you can always get back on the ship and get more $$. The pursers office will cash travelers checks. I did not try to cash travelers checks off the ship. I did notice that the "cruiseline sponsored " shops did accept most major credit cards, travelers checks, and american currency. Carry small bills (to provide exact change)as many vendors will try to give you change in the "native currency". Which you can ususlly exchange at the pursers office, but who knows if you are getting correct change.