Haiti is only about 200 miles from Gitmo. Half hour flight, give or take.
Apparently the USCG patrols the waters off Port au Prince somewhat, so ferry service is really limited.
Check out:
https:// www.tripadvisor.com/ShowTopic-g147307-i1244-k6713629-Traveling_via_boat_to_haiti-Port_au_Prince_Ouest_Department_Haiti.html
"Shipping companies, of course, do sail to Haiti from Florida and New York. That is also tightly controlled and shipping companies really have no interest in dealing with passengers and the complications they involve."
Unless your passengers are packed into a shipping container.