After Dream's problems began Wednesday, Gregg Stark, who is traveling with his wife and two young children, told CNN that conditions were deplorable.
"There's human waste all over the floor in some of the bathrooms and they're overflowing -- and in the state rooms," he said. "The elevators have not been working. They've been turning them on and off, on and off."
An announcement over the ship's public address system said the crew was trying to fix the problem and was working on the generators, according to Stark. A few hours later, another announcement said the problem was worse than originally believed.
"We are not allowed off of the boat despite the fact that we have no way to use the restrooms onboard," Jonathan Evans of Reidsville, North Carolina, said in an e-mail Thursday. "The cruise director is giving passengers very limited information and tons of empty promises. What was supposed to take an hour has turned into 7-plus hours."
But Thursday afternoon, Carnival told CNN that based on conversations with the ship's management team, a look at service logs "and extensive physical monitoring of all public areas, including restrooms, throughout the night, we can confirm that only one public restroom was taken offline for cleaning based on toilet overflow and there was a total of one request for cleaning of a guest cabin bathroom.
"Aside from that, there have been no reports of issues onboard with overflowing toilets or sewage. The toilet system had periodic interruptions yesterday evening and was fully restored at approximately 12:30 a.m. this morning."
'This needs to change'
Last month, an engine room fire left the Carnival Triumph adrift in the Gulf of Mexico with more than 4,200 people aboard.
As that scheduled four-day cruise doubled in length, food was scarce, and passengers sweltered in the heat with no air conditioning. Passengers also reported overflowing toilets and human waste running down the walls in some parts of the ship.
A class-action lawsuit was filed against Carnival Corp. afterward.
The Triumph is still being repaired at a shipyard in Mobile, Alabama, Carnival spokeswoman Joyce Oliva said.
"We are now focused on the lessons we can learn from the incident and also what additional operational redundancies might be available," Cahill, the Carnival president, said this week.
Another ship, the Carnival Splendor, had a fire in 2010 due to "a catastrophic failure of a diesel generator," he said.
In a Friday news release, Carnival said total advance bookings for 2013 are behind 2012 levels, but since January, booking volume for the rest of the year has been "running significantly higher than last year," despite "slightly higher prices."
"Despite considerable attention surrounding the Carnival Triumph, we had been encouraged to see booking volumes for Carnival Cruise Lines recover significantly in recent weeks," said Micky Arison, chief executive officer of Carnival Corp.
"Attractive pricing promotions, combined with strong support from the travel agent community and consumers who recognize the company's well-established reputation and quality product offering," were the reason, he said.
Nevertheless, Carnival stock sank Friday after a weak forecast for sales and profits this year.
Sen. Jay Rockefeller, chairman of the Senate Commerce, Science and Transportation Committee, sent a letter Wednesday to Arison.
"The Coast Guard has responded to a string of 90 marine casualty incidents with passengers onboard Carnival ships in the last five years," the West Virginia Democrat wrote. "It seems that Carnival has failed to take any meaningful course of corrective action after these continual incidents. This needs to change."
Despite all the recent problems, Donahue doesn't see any long-term negative effects for Carnival or its competitors.