Passengers protest aboard Norwegian Spirit cruise ship

The disappointment started mounting the first day of a two-week Norwegian Cruise Line voyage in Europe.

So by the time the Norwegian Spirit had diverted to several alternative ports - spending extra unplanned days at sea - passengers were on edge. They had already missed out on Iceland, the trip's main attraction. By Monday, a week and a half in, travelers were gathered with their bags and cameras, looking forward to being on land again in Scotland.

As the 2,018-passenger vessel neared shore, according to two passengers, a voice came over the public-address system announcing that weather would prevent it from making yet another stop.

"That's when the riots broke out on the ship," says Cody McNutt, 31, of Denver, who was onboard with his girlfriend and family members.

"There was an instant uproar," his girlfriend, Katasha Jones, says. "The tension leading up to the announcement was palpable and then it just exploded, and people just went over the edge."

What followed was a prolonged protest as passengers shouted demands for a refund, held up homemade signs, called crew members liars and asked to go back to London to get off the ship. The revolt lasted for hours, Jones and McNutt said.

"No one was violent, and I think people were as respectful as they could be with as upset as they were," Jones said. "At a certain point, you can't blame people for being upset. At a certain point, you just lose it."

McNutt said workers onboard told passengers to call the company's headquarters in Miami. He said he tried and was told to speak to the guest-services department on the ship.

"A refund is nice, and that would be great, but I really want the CEO or somebody to apologize for what they're doing to people," he says.

In a statement, the Miami-based cruise line said the ship's itinerary was disrupted due to "severe weather conditions" and the ship was only able to call on eight ports rather than the scheduled nine. Norwegian did not say how many of those ports were substitutions."

We understand that it is disheartening when we are unable to call on ports that our guests have been looking forward to visiting," the statement said. "However, we do ask for our guests' patience, cooperation and understanding that severe weather conditions are an act of God and cannot be controlled, influenced or remediated by the cruise line. Our goal is to showcase the beautiful destinations our ships visit and to provide guests with an onboard experience that is second to none."

The statement apologized for passengers' inconvenience and disappointment, but did not address the protests.

"We always do our best to provide our guests with a truly enjoyable and memorable vacation, but our very first priority is to ensure their safety and the safety of our crew," the company said. A photo of a letter dated Oct. 7 showed that the company was offering passengers a 25% discount on future trips "to demonstrate our gratitude for your patience."

"That set everyone off again," McNutt says. "None of us want to get on their ships ever again." He said the toilet in his room stopped flushing, and Jones said she encountered a public toilet that did not work as well. They said they smelled sewage early in the morning.

After boarding the ship Sept. 27, McNutt and Jones left early. The cruise is set to end Friday in Southampton, England, but the pair got off Tuesday during a planned stop in Belfast, Ireland. They took a train to Dublin and started their journey home, with a layover in the one place they had really wanted to see.

"We're the only two on the ship that are actually going to get to go to Iceland," McNutt said Wednesday.

Colleen McDaniel, editor-in-chief of the review and news site Cruise Critic, said in an email that minor itinerary changes aren't out of the ordinary, especially during hurricane season.

And, she said, strict cruise line contracts give operators the right to change their plans whenever necessary.

"When itinerary changes happen, we do tend to see disappointment from guests. But for the most part, cruisers understand that these changes can happen and are usually a result of the lines dealing with situations outside of their control," she said. "During hurricane season, we've seen complete itineraries swapped -sometimes Caribbean cruises are redeployed to New England to avoid storms, for instance.

"It's never an ideal situation, and we do hear disappointment, but it's a result of unsafe conditions and cruise lines reacting so as to keep passengers as safe as possible."