Twice a year airline employees who have some time on their hands, can take advantage of extremely favorable interline rates on Transatlantic repositionings.
These happen in the Spring when some ships leave their Caribbean itineraries and head over to sail in the Med and European waters. Others leave Florida and sail via the Panama Canal to Seattle or Vancouver for the start of the Alaska season in May.
In the Fall those ships reverse direction and return to the Caribbean for the Fall/Winter season. Because the cruise lines have to “reposition” those ships across the pond or for Alaska they offer very favorable interline discounts.
So if you have 12-18 days to spare and want a leisurely cruise to Europe from North America, these sailings are fabulous interline deals.