"I appreciate the patience of our guests and their ability to cope with the situation. And I'd like to reiterate the apology I made earlier. I know the conditions on board were very poor," he said. "We pride ourselves on providing our guests with a great vacation experience, and clearly we failed in this particular case."
While the passengers are headed home, Triumph will head to a Mobile shipyard for assessment, Thornton said.
Earlier Thursday - four days after the 893-foot ship was crippled in the middle of the Gulf of Mexico - the passengers and crew suffered another setback with towline issues that brought the vessel to a dead stop for about an hour just when it was getting close to port.
As the vessel drew within cellphone range Thursday, passengers vented their anger.
Renee Shanar of Houston was on board with her husband, who she said has heart trouble. They were told they will be among the first to disembark, she said.
"I don't believe them; they've been lying to us from the beginning," Shanar said.
Disgusted by the foul air and heat on the lower decks, many passengers hauled mattresses and bed sheets onto the top deck and slept there, even staying put in a soaking rain. As the ship approached the coast, a slew of Carnival workers removed the bedding and took it downstairs.
"Today they cleaned the ship, they're serving better food, covering up basically, but at least they're making it more bearable," said Kalin Hill, of Houston, who boarded the Triumph as part of a bachelorette party.
In a text message, though, she described deplorable conditions over the past few days.
"The lower floors had it the worst, the floors 'squish' when you walk and lots of the lower rooms have flooding from above floors," Hill wrote. "Half the bachelorette party was on two; the smell down there literally chokes you and hurts your eyes."
She said "there's poop and urine all along the floor. The floor is flooded with sewer water ... and we had to poop in bags."
The company disputed the accounts of passengers who described the ship as filthy, saying employees were doing everything to ensure people were comfortable.
Some travel agents said cruise prices and bookings have not been affected by the disabled Carnival ship, but others in the industry say it's too early to tell.
Thelbert Lanier was waiting at the Mobile port for his wife, who texted him early Thursday.
"Room smells like an outhouse. Cold water only, toilets haven't work in 3 1/2 days. Happy Valentines Day!!! I love u & wish I was there," she said in the text message, which was viewed by The Associated Press. "It's 4:00 am. Can't sleep ... it's cold & I'm starting to get sick."
Carnival said the original plan was to tow the ship to Progreso, Mexico, because it was the closest port, but by the time tugboats arrived, the ship had drifted about 90 miles north due to strong currents, putting it nearly equidistant to Mobile. It was also logistically easier for the company, which said costs were not a factor.
Carnival has canceled a dozen more planned voyages aboard the Triumph and acknowledged the crippled ship had been plagued by other mechanical problems in the weeks before the engine-room blaze. The National Transportation Safety Board has opened an investigation.
Passengers were supposed to get a full refund and discounts on future cruises, and Carnival announced Wednesday they would each get an additional $500 in compensation.