Not necessarily, but confirm.
I've flown there three times, all were IFR flight plans. You will have to have an international flight plan filed along with a pre-approved passage number. This can be obtained from an office in the Miami airport or from the FBO at Grand Cayman. Be sure you do this well ahead as you will have to give them a passenger and crew list. Hope your "N" number has never been spotted dropping leaflets or you'll go the long way. Also check AOPA for regulations.
I left Ft Pierce, Fl to Marathon and straight over Cuba (Giron corridor). They speak English well, just do not speak Spanish unless you are very fluent. It comes back fast.
Fun trip, longest stretch not more than 45 minutes(over open water) in the Bonanza or Baron. About the same for the RV.
David