Cruise in the caribbean?

I have never taken a cruise, and believe I would hate it. (Especially after reading David Foster Wallace’s essay: “A supposedly fun thing I will never do again”... )

Given all that, I might have five days in April, and I have never been to any of the Caribbean Islands, and it occurs to me that since swimming and beaches would be my goal here (and not big city activities), a cruise might work, if it is the right kind.

And just what might that be? Small, enough time to spend a good afternoon at beaches, and the kind of people that would prefer a non-big fancy type cruise. Does such a thing exist?