New Orleans —Margaret and Scott Douglass, of Sugarland, Texas, boarded the Carnival Triumph in Galveston on Feb. 7 to celebrate their 26th wedding anniversary with the first vacation they’ve taken alone together in as many years.

A week later, the couple was still on the Triumph, close enough to the Alabama coast to see land — “We could swim there,’’ Margaret Douglass said Thursday from the vessel by cellphone — but trapped on what she described as a listing, reeking cruise ship.

The cruise to Cozumel was supposed to be a short one — four days and one port of call.

The first two days, Friday at sea and Saturday at Cozumel, were perfect, Margaret Douglass said.

But about 5:30 a.m. Sunday, she heard an announcement: “Alpha team report to Level Zero.’’

She said she immediately knew that meant there was a problem.

“I got into Titanic mode,’’ she said.

She got dressed and went into the corridor, where she could smell smoke and noticed that all the fire doors were closed. When she opened a door, she said, the stairwells were filled with smoke.

The ship’s crew announced about 6:15 a.m. that a fire had occurred in the engine room but it was too hot for anyone to go inside to check, she said. That announcement was repeated throughout the day.

The passengers were finally told, at about 8 p.m., that there would be no more power, she said.

Initial attempts to tow the Triumph, with one tugboat from Mobile and another from Progresso, Mexico, failed, Douglass said.

The line on the Mexican boat broke four times in the attempt, she said, something she said was frightening because the Triumph shuddered with each break.

Days of misery followed, without power, without water and without hot food, she said. Passengers were instructed to urinate into the shower drains and were given red bags for solid waste, she added.

But because the boat had no power, it was listing, Douglass said, making it harder to use the shower as a urinal. Douglass said she and her husband used cups, so they could pour carefully into the drain. But when she went to another level of the ship, she said, the reek of waste was overwhelming, and the carpets were soaked.

“It was disgusting,’’ she said.

Food was mostly limited to cold offerings, she said, tomato and mozzarella sandwiches for the most part, although she noted that the U.S. Coast Guard had brought in Sterno on Wednesday night, so passengers had hot eggs Thursday morning.

Douglass and her husband plan to salvage what they can of their anniversary trip by spending a few days in New Orleans, where their son, Sean, lives.

Passengers were told they would arrive in Mobile, Ala., Thursday night, she said. They were given the option of being taken directly to Galveston by motor coach, she said. Everyone else would be taken to New Orleans on Thursday night to stay at the Hilton Riverside, although Douglass said that they were told it could end up being somewhere else. Douglass said she and her husband decided to take no chances and booked their own room.

She also made sure that her family was taking care of business back home. A sign that she made and posted for her balcony was filmed by CNN. The message: “Sean, Kyle, Conner, I love you. Clean the cat box.”