The spring and summer months may bring a decrease in the number of cruises departing from Miami, but that’s just a relative thing: there are still over 40 cruises every month leaving for the Caribbean and the Bahamas.
Carnival, Norwegian and Royal Caribbean all have ships that set out on 3- and 4-night cruises every week. The 3-day voyages are to the Bahamas and leave every Friday. On Mondays those same ships (Carnival Imagination, Norwegian Sky and Majesty of the Seas) make 4-night trips, with Majesty of the Seas and Norwegian Sky making longer trips back to the Bahamas and Carnival Imagination taking a short trip through the Western Caribbean.
If you have a week to spend traveling the Caribbean, Carnival Valor alternates 6- and 8-day voyages, mixing things up between the Eastern, Western and Southern Caribbean. Valor’s sister ship, Carnival Liberty, sticks to a 7-day schedule, alternating between the Eastern and Western Caribbean.