How can person traveling alone book a cruise without paying double?
There are at least two cruise lines, Holland America and Carnival that do not change double. You will probably pay 1 1/2 times the fare. However, if you book late and there is a lot of space left, contact the cruise line directly and see what you can negotiate. Also most cruise lines include their port charges in their fares. See if they will at least deduct the charges for a second non-existant person. If you have to pay double try and get an upgrade.
I don’t think you can avoid it. Cruise lines want to get the most money and the fullest ship they can so of course if you have 2 beds in a room you’ll have to pay double occupencey. My only suggestion would be to find a friends to go with you! Its much more fun to go with someone. Royal Caribbean is a GREAT cruise line to go on. They are a great line.