Amid one of the worst downturns in American history, consumers are benefiting from hot deals and massive markdowns offered by cruise lines.

Prices are being cut by as much as a third, industry participants say.

“No one wants to sail on an empty ship,” said Kris Krenz, of Pak and Go Cruises and Tours of Brick, NJ.

A four-night cruise on Carnival Cruise Lines to the Western Caribbean starts at just $109 for an interior room, and $149 for an ocean view, while a five-day trip to Baja Mexico starts at $249. Norwegian cruise lines boasts seven-night Bahamas cruises from $399, and trips to Alaska for $499. Royal Caribbean is promoting a seven-night Southern Caribbean cruise from $349; rival Celebrity Cruises is recommending its 10-night Eastern Mediterranean cruise from $649.

“There has been at least a 50 percent increase in the amount of deals and promotions that cruise lines have been offering,” Krenz said. “The truth is that the ships are not filling up. The severity of the economic conditions is really hurting the industry.”

This is turning into one of cruise lines’ most painful off-peak seasons since the September 11 terrorist attacks.

“It really kills these cruise lines to sell brand-new ships for next to nothing,” said Cruise Holidays Kansas City general manager at Patti Edwards. “The hope is that some of the money will be recouped in the upcoming January-February [2009] season.”

This glimmer of hope is what many cruise lines are holding on to as winter approaches, and cruise deals hit rock bottom.

“We are constantly running promotions in an attempt to keep our ships at capacity,” said Celebrity Cruises representative Lisa Webster. “The coming season is our hope.”

But critics are skeptical of how much of a boost the next month or two will bring to the cruise line industry, given depth of the economic distress.

“People have really been holding back on spending anything extra,” said Krenz. “Additionally, people who usually cruise twice a year have scaled back to one, if any at all.”

Phil Swartz, the founder and owner of Cruise Holidays of Tallahassee, has a different view. He expects a rebound this winter.

“I am very optimistic that things will change, and cruise lines will recoup all of their money in the coming months,” he predicted. “People may downscale from a 10-day European cruise to a seven-day Caribbean cruise, but no matter what, I believe that they will still go.”