PHOTO: Viking Ocean Cruises’ Circle Pacific Cruise itinerary. (photo by Jason Leppert)

There are hundreds of cruise ships and thousands of international cruise ports to deploy them to.

It seems like it would be an easy formula to plan itineraries accordingly, but as more and more mega vessels come online, it becomes increasingly difficult jockeying for prime positions.

Think of it this way: The two classic cruise regions that everyone considers first are the Caribbean and Mediterranean. Within each are dozens of destinations that are popular and much-frequented. Caribbean ports like Grand Cayman or Mediterranean ones like Civitavecchia for Rome can literally line up with ship after ship.

Those that are there have likely secured a spot several years in advance.

So, when the next “world’s biggest cruise ship” comes out, it can’t just go anywhere it wants on a whim. Planning must be done well ahead of time.

The first step is to determine where any ship is going to embark and disembark passengers at the start and end of a cruise. Weeklong sailings remain the sweet spot, and most passengers want to leave as close to a weekend as possible. Of course, that means somewhere like Miami will be most saturated on Fridays, Saturdays and Sundays.

The best luck cruise lines have to find any new openings then is to develop new terminals that can handle additional or at least, bigger, ships.

As the largest and newest displace existing vessels, the older smaller ones have to go to other homeports, and those destinations likely have to improve their infrastructure to even accept them. The story is true for global ports of call. In order to accommodate the latest hardware, piers have to be upgraded to handle it.

While there may be thousands of cruise destinations internationally, there’s a smaller subset capable of accepting the grandest ships. Today, vessels are still required to anchor off shore and inconveniently tender passengers to a marina—even at some cruise line’s own private destinations.

More often than not, smaller ships have the easiest time of selecting ports to sail to.

Clearances are such that they can get into much tighter bays and inlets, and older piers can more easily tie them off. That’s why some new-builds are trending away from mega cruise vessels and why they can feature more distinct destinations off limits to big ships.

Regardless of ship size, once a point of embarkation and a first port of call are reserved, the challenge is then finding a whole string of available ones to make up an itinerary lasting anywhere from a couple of days to months. Of course, they have to be within relatively close distance to one another too.

It quickly becomes quite a puzzle to solve, particularly for mainstream cruise lines that regularly return to the same areas.

Many other brands can at least branch out and hit up seasonal regions or more popular destinations during off times. Alaska and Canada and New England are seasonally popular, and the Mediterranean eases up some more towards the fall, for instance.

In places like the Caribbean—where the crowds are essentially present year-round—the best solution has seemed to be for the cruise lines to develop more of their own private destinations. Not only can they better control the quality of the guest experience, but they also provide an entirely new place to go free of other ship and passenger congestion.