Today, yet another cruise ship with a suspected norovirus outbreak found itself back in port early, though a spokeswoman for the cruise line said fog was to blame for the return.

Princess Cruises' Caribbean Princess was on a seven-day trek out of Houston, with a final stop in Belize. There were more than 4,200 people on board.

Related: Why norovirus is so nasty and terrifying to travelers.

The cruise ship line said, however, that it decided Wednesday to cut the trip short by a day because of forecasts of fog on the route, not because of the outbreak.

Julie Benson, a Princess Cruises spokeswoman, blamed a Houston port closure on the ship's early return. She said the cruise line was told the port would likely be closed because of fog.

"If we did not have the potential of the closure of the port because of fog, we would not have come in early," Benson told The Associated Press.

Passengers, however, cried foul.

Steve Juneau and Robert Fischer of Houston were confined to their cabin for three days because Fischer had fallen sick.

"The cruise was bad. Tons of people were sick on board," Juneau said. "We didn't get to enjoy [any] of the meals, any of the shows. … It was terrible. They canceled Belize, which was the main reason people came on this cruise."

The cruise ship, which was carrying more than 170 sick passengers and crew, kept sick passengers in their cabins, Benson said.

"I wanted to get out. I was tired of being held as a prisoner in the room," Fischer said. "They didn't bring food. … We had to call and remind them every time."

Others questioned whether fog was really the reason for the early return.

"We knew it was a lie [about the fog] when they said it," said Terry Bible of Woodville, Texas. "The port is not going to close down for three days due to fog."

As those passengers headed home, a team from the Centers of Disease Control and Prevention boarded the ship to investigate and the boat underwent an extensive cleaning.

In New Jersey today, the CDC confirmed that the norovirus was in fact what had sickened nearly 700 people on the Royal Caribbean's Explorer of the Seas earlier in the week. The norovirus is very contagious. It survives on surfaces and hands and can spread throughout a ship.

That ship ended a 10-day cruise from Liberty, N.J., to St. Maarten two days early.

Today, Royal Caribbean said the ship had been scrubbed from top to bottom since it docked Wednesday. Passengers boarding the Explorer of the Seas for another trip told ABC News today they were hoping for the best.

"We feel that this is maybe the safest cruise ship to be going on," said Gina Hull of Dover, Del. "It's been cleaned for two days. … I'm sure everything will be all right."

ABC News' Gio Benitez and Diane Mendez contributed to this story.