A passenger on an ill-fated cruise ship that docked in San Francisco after an outbreak of the highly contagious norovirus described the vessel “a floating Petri dish.”

Peter Korer, 60, a veteran cruiser from Las Vegas, told The California Post that he was excited for the Ruby Princess’s 20-day Alaskan voyage leaving June 12 from the Bay Area.

Instead, he was met with sick passengers and strict disease protocols on board just days into the trip. In all, more than 100 passengers and 20 crew members showed symptoms of the stomach-churning virus.

Korer said it was his first experience in more than 40 cruises dealing with norovirus.

He first heard about the outbreak when the ship’s captain came over the PA system around dinnertime on June 15 to deliver the awful news.

“The captain came on, said there’s been people, you know, with reported symptoms,” Korer explained.

“If you have any of these symptoms, report immediately to the medical center, and we’re going to go into deep cleaning.”

The announcement came after the ship had just stopped in its first Alaskan destination, Ketchikan. It hadn’t yet docked at its other stops, including Glacier Bay National Park and college Fjord.

Crew began cleaning the ship immediately, ordering infected passengers to stay in their quarters for at least 24 hours after they last experience symptoms, Korer recalled.

He said gloved workers served passengers their food at the buffet, while those who quarantined were served food outside their rooms.

Korer, who never got sick during the voyage, took precautions like staying away from crowds, washing his hands and wiping down everything he touched.

He said the ship’s staff asked him and other passengers to leave their rooms for a designated time during the cruise for deep cleaning. Otherwise, he worked remotely during the tripo and enjoyed the spectacular frozen sights.

“Besides the constant cleaning of everything, and the buffet being served by the employees and not self-serve. It was a typical normal cruise,” Korer said. “Everything was fine.”

The ship arrived back in San Francisco on July 2, and passengers disembarked before the vessel underwent “comprehensive cleaning and disinfection,” said the ship’s operator, Princess Cruises.

The company added only a “limited” number of guests came down with illness. The CDC reported that 3.4% of the vessel’s 3,032 passengers and and 2% of the ship’s 1,144 crew reported being ill. Most symptoms included diarrhea and vomiting.

“Princess Cruises can confirm that a limited number of guests reported mild gastrointestinal illness during the 20-day June 12 Ruby Princess voyage from San Francisco,” the company said in a statement. “Our crew responded promptly by implementing enhanced sanitation protocols across the ship, and cases have since decreased and remain low.”

It marked the third norovirus outbreak on the cruise line since March, after the Star Princess and Caribbean Princess ships were also affected. The outbreak on the Caribbean Princess sickened over 100 passengers and more than a dozen crew members during its 14-day voyage through the Eastern Caribbean.

Norovirus is the most common cause of gastrointestinal illness outbreaks on cruise ships, according to the CDC. The disease accounted for 17 out of the 23 CDC-reported cruise ship outbreaks last year.

For his part, Korer said the experience wouldn’t dissuade him from going on another Princess Cruises trip.

In fact, he immediately embarked on a new journey after the shipped docked in San Francisco.

“I got off the Ruby Princess, went down the street, and jumped on this one,” he said of the Carnival ship he got on next.