Just like airlines, cruise lines occasionally overbook their ships. And just like the airlines, cruise lines seek out volunteers willing to accept compensation to reschedule their cruises. But unlike airlines, we've never heard of a passenger being forcibly bumped -- until now.

In a thread posted on Cruise Critic's message boards, member Zebra explained how four days before her June 11 four-night Monarch of the Seas Bahamas cruise, a Royal Caribbean representative called to say her ship was overbooked and she was being bumped. She had booked the cruise, which departs from Port Canaveral, 10 days earlier in a guaranteed inside cabin.

Though all cruise lines reserve the right in their cruise contracts to cancel, deviate or substitute a cruise for any reason, the common practice is to seek out volunteers and not force anyone off a ship that's been overbooked.

"RCCL called to say that they apologize but they have overbooked this cruise so we have three choices," she wrote. According to a cruise line representative, she could trade in her inside guarantee for the same itinerary departing on the same day but from Miami, a four-and-a-half-hour drive from her home, on Majesty of the Seas. For her trouble, Royal Caribbean would provide an upgrade to an oceanview stateroom and an additional $100 onboard credit. A second option was to reschedule her cruise on Monarch of the Seas for a later date, with the same oceanview bump-up and $100 in onboard credit. Or she could simply cancel and get a full refund.

Whichever option she chose, the one choice she wasn't given was for her cruise to take place on the ship and on the date she booked. After Zebra requested more compensation (the line ultimately raised the offer to $300 onboard credit), she chose the Miami alternative. But in her eyes this bumping was anything but voluntary.

An effort at clarifying the issue with Royal Caribbean went unrewarded, as spokesman Harrison Liu would only tell Cruise Critic that “someone had volunteered and accepted compensation to reschedule their cruise vacation." Liu would not respond to requests for further clarification.

We're not sure if he's talking about the same person, but Zebra is sure she didn't volunteer. "We were not given the option at all to stay on the ship," Zebra told Cruise Critic in an e-mail. "They told us twice 'You have three options,' so we did not pursue the issue of staying on the Monarch."

Cruise seller Tim Martin, owner of an Oregon-based CruiseOne location, said he has never encountered a situation like Zebra's. Booking so close in and on a guarantee basis was probably a factor, he told Cruise Critic.

"If it was my client," Martin said, "I would be reviewing the cruise contract to see how much wiggle room I had."

With that said, we can't help but wonder how much wiggle room Zebra might have had as well. She didn't push her case of staying on her originally booked cruise. But what if she had? Would Royal Caribbean have forced her off? Or would the cruise line have backed down?

To learn more about bumping, and what to do if you're bumped, see our feature, Could You Be Bumped from Your Next Cruise?

Personally after 9 cruises since 2002 I have never heard of anything like this happening. People get removed from ships but its usually for bad behavior. has anyone ever heard of a passenger being bumped for overbooking?