If the explosion of Iceland's Eyjafjallajökull volcano earlier this month has proven anything, it's that the world has become too reliant on the airplane. I mean, really: Should a cloud of ash really be permitted to bring travel and commerce in a big chunk of the globe to a standstill? Shouldn't we have a fallback plan? Shouldn't we have, for instance, ships?

True enough, but as this week's events have proved, the world's shipping companies are not immune to major volcanic incidents. Today's global travel industry is just too interconnected, with cruise passengers almost invariably getting to their ships by plane -- or not getting there, as the case may be.

According to Cynthia Martinez, manager of corporate communications for Royal Caribbean Cruises Ltd. (RCCL, parent company of Royal Caribbean, Celebrity, and Azamara), this week's airport closures in the United Kingdom, Ireland, and northern Europe have affected some 6 percent of the three lines' guests. Of those 6 percent, some were unable to reach their ships, while others were unable to get home after their cruise. Since the three lines' total double-occupancy capacity is about 75,500, and since the airport closures fell over a weekend (the turnaround time for most cruises), that 6 percent may represent upward of 9,000 guests -- significant for RCCL, but really a drop in the bucket considering that the total number of travelers displaced or disrupted by Eyjafjallajökull has been estimated at more than 7 million.

It could have been a lot worse for the cruise lines. Had Eyjafjallajökull waited another month to erupt, it would have coincided with the first full weeks of the summer Europe cruise season and disrupted the plans of many thousands more passengers. Currently, only a handful of ships -- aside from those operated by Europe-based lines -- are in the Mediterranean or northern Europe, and some of those that are have been pressed into service to aid stranded holiday-makers.

On Tuesday, Celebrity Cruises ( pulled its new 122,000-ton, 2,850-passenger Eclipse from her planned inaugural celebrations and sent instead to Bilbao, Spain, where on Thursday morning she's scheduled to pick up some 2,000 British vacationers who've been stuck for a week. The rescue mission was arranged in collaboration with TUI UK (parent company of tour operators Thomson and First Choice), Thomas Cook, and The Co-operative Travel Group (CTTG), who are handling the transport of British travelers from across Spain to the port of Bilbao.

Such was the interest in the ship's so-called "repatriation sailing" that Celebrity was moved to issue a statement advising customers of other tour operators "to NOT turn up at the port in the hope of traveling with Celebrity Eclipse. Whilst we want to get as many people home as we can, we are only able to transport customers traveling with First Choice, Thomson, Thomas Cook, and CTTG."

Thomson's seagoing division, Thomson Cruises (, undertook its own repatriation cruise this week, pulling the 1,741-passenger Island Escape off its Mediterranean sailings in order to return its passengers to the southern U.K. port of Falmouth, rather than leave them stranded in the Med. Some 300 other travelers who'd booked land vacations through Thomson were also accommodated aboard Island Escape, which is expected to reach Falmouth today, April 22.

(Europe's airspace began re-opening on April 21, while the repatriation sailings were still at sea. However, since air travel remained chaotic as airlines struggled to accommodate the backlog of stranded travelers, I figure those people aboard Celebrity Eclipse and Island Escapeare happy they took the sea route).

Disrupted travel within Europe is bad enough, but problems are complicated when travelers and their destinations are separated by the Atlantic Ocean. Cruise lines that are currently or will soon be sailing transatlantic cruises found their phone lines buzzing this past week with travelers looking to hop the pond the old-fashioned way.

Cunard's Queen Mary 2

(, the only ship currently operating a regular transatlantic schedule for at least part of the year, fortuitously began its transatlantic season just this week. The ship's booked passengers suddenly possessed of some of the few "get out of Europe free" cards in the world.

The first run, sailing from Southampton to New York, departs today, April 22. A return voyage sails New York-Southampton on April 29. Both, says a Cunard volcano statement, "are sold out with a lengthy waitlist; Cunard is handling new bookings on full sailings as cancellations occur."

Cunard's sister-line, Princess Cruises (, also saw what it called "unprecedented demand" for three upcoming eastbound transatlantic cruises: Ruby Princess's 16-night Ft. Lauderdale-Barcelona cruises, which departed April 20; Star Princess's 18-night Ft. Lauderdale-London cruise, departing April 24; and Crown Princess's 14-night Ft. Lauderdale-Rome cruise, which departs May 1. Currently, only the May 1 cruise has any availability.

Beyond providing a possible transatlantic option to travelers who were either very determined and/or worried about predictions of another debilitating Icelandic ash cloud, Princess has also had to deal with the situation aboard Sea Princess, which carries predominantly British passengers. According to Julie Benson, the line's VP of Public Relations, Sea Princess "was supposed to disembark and embark about 900 passengers in Barbados April 17, but since our air charters could not operate, [the guests] stayed onboard the ship, and we are at this moment working with our U.K. charter carriers to come to Aruba on April 22 to fly them home."

Other lines in Europe resorted to providing extended hotel stays for debarked passengers or shuttling them home through some combination of buses and ferries. Worth noting is that these courtesies only apply to guests who booked air transportation through the cruise lines: For the other folks, who booked air on their own, the cruise lines' obligation ends when passengers walk off the gangway. Ditto for any recompense if a passenger is unable to make it to the port of embarkation and misses the ship. Sister lines Royal Caribbean, Celebrity, and Azamara, as an example, are offering guests who were unable to make their April 17, 18, or 19 sailings "a refund of their airfare and a 100 percent Future Cruise Certificate in the amount of the cruise fare paid" -- as long as they made their air arrangements through the line. The three lines advise those guests who purchased air arrangements independently to contact their airlines and travel insurance providers. In other words, they might just be SOL.

Moral of the story? When it comes to travel, Mother Nature still rules. As much as we might believe that we've made the world safe and convenient for holidays and commerce, all it takes is one little volcano in a country with .005 percent of the world's population to blow our whole international travel system all to hell.

Road trip, anyone?