The cheapest way to spend two weeks on a large cruise ship is usually a voyage that exists only because the ship has to be somewhere else. The pricing follows directly from that.
The passage is compulsory
Cruise ships follow seasonal deployment. A vessel working one region in summer works another in winter, and it must physically cross between them twice a year.
That crossing will happen whether or not passengers are aboard, and the fuel, crew and port fees are largely committed either way.
Selling the passage therefore recovers cost on a trip the operator cannot avoid, which is a different calculation from filling a peak-season week.
The product is structurally different
A repositioning voyage is mostly sea days, because the distance is long and the coastline between the two regions offers few useful calls.
Sea days cost the operator less in port fees and pilotage, and they generate more onboard spending per passenger than a port-heavy itinerary.
The itinerary is also one way, which suits far fewer travelers than a round trip from a homeport near where they live.
One way travel is the hidden cost
The saving on the fare is partly offset by needing a long flight home from the far end, often intercontinental and often one way.
One way air is priced less favorably than a round trip on many routes, and the return is at a fixed date that limits fare options.
Travelers who evaluate the cruise fare alone frequently find the total lands closer to a conventional voyage than the headline suggested.
Timing is fixed by the season
These voyages run in narrow windows at the shoulders of the seasons, which is when the departure and arrival regions are both operationally ready.
That timing also means crossing weather can be unsettled, since the ship is moving because the season is turning.
Itineraries are written with sea days that can absorb a slow passage, so a rough stretch usually costs comfort rather than a missed port.
Who the format suits
Anyone who values sea days, has time flexibility and is comfortable with a long flight in one direction gets the most days aboard per dollar of any cruise format.
It suits repeat cruisers in particular, since the appeal is the ship rather than the destinations, and the onboard program is built around that.
It suits families and short-vacation travelers least, because the length is fixed by the distance and cannot be trimmed to fit a week off.