Gone are the days of one-price-pays-for-it-all cruising as the cruise lines have adopted a more flexible À la carte approach to cruise pricing somewhat similar to the airlines' unbundling of baggage fees and the offering of premium seats with more leg room at additional costs. The benefit of this approach is that it more directly allocates costs to the cruisers who utilize specific services on a ship while also allowing the cruise line the freedom to offer more premium services that would be cost prohibitive without the ability to charge extra. The result is bare-bottom pricing which opens up cruising to a much broader segment of the population who previously may have not been able to afford a cruise at an all-inclusive price.
Below are some examples of premium onboard expenses for services available on Royal Caribbean's Oasis of the Seas, the largest cruise ship in the world.
There are also many other premium services that one would expect to pay extra for such as spa treatments and top shelf liqueur and wine, and It's up to the cruiser to determine if they want to avail themselves of these premium services or be as frugal as possible by sticking to only those items covered as part of the cruise booking price.