How cruise ships fill their unsold cabins.

When it comes to filling unsold cabins, cruise lines have basically got to be very creative, especially the closer that it gets to sailing day. In an ideal world from their point of view, ships would go out full on each and every sailing. 

This kind of creativity surfaces on a number of fronts. 

For instance, some lines might waive the usual single supplements, in a bid to get more solo travellers on board. They might also upgrade already booked past passengers, especially if they are part of a company loyalty programme, and then sell the freed-up cabins to new potential passengers. 

But these are not the only arrows at the cruise lines' disposal. They can lure the potential passenger on board by offering a range of on board credits (OBC in industry speak) that can be used to pay for on board drinks, shore excursions, spa treatments, and sometimes even in the shops on some lines. 

They can offer free or substantially discounted internet packages to passengers, as well as two-for-one fares that allow a couple to travel together at a single price. 

For many passengers, one of the best lures out there can be the offer of free air fares on fly cruises, or sometimes complimentary upgrades from economy to business class. This is an option that is particularly popular on cruises sailing from and to European ports.

Additional incentives can be dangled before the prospective passenger, including free overnight hotel stays in the port of embarkation, either pre or post cruise. And, for regular patrons of any given cruise line, loyalty bonuses can often come into play, reducing the cost of a cruise by anything from between five to ten per cent, and sometimes even more. 

As more and more ships enter service, expect cruise lines to get more creative still in their attempts to get you on board. For instance, off season sailings in the Mediterranean can be priced at less than half the cost of the same voyage in peak season, with the advantage of smaller crowds at the main tourist sites. The drawback here- and everything is a trade off to a certain extent- is the cooler weather. 

Similarly, taking a back to back voyage in the Caribbean- effectively, combining two cruises- also usually works out a lot cheaper, with the lines emphasising that you are only paying one airfare.