The crew of the Diamond Princess had gone the extra mile on Friday – as they have done so often during their ship’s quarantine off Japan – with Californian wine and a dinner menu that included “Cupid’s avocado and shrimp”, coq au vin and a “surprise dessert of the day”.

But for the thousands of passengers forced by the coronavirus outbreak to remain inside their cabins for the best part of two weeks, Valentine’s Day rituals must have seemed like they belonged in another world.

quarantinedondiamondprincess (@quarantinedond1) Day 9: We have our Valentine’s Day Dinner plans! #quarantine #DiamondPrincess #loveboat pic.twitter.com/dMr8HVvyNm

As they entered the last leg of their isolation at Daikoku pier in Yokohama, south of Tokyo, some passengers, whose luxury cruise ship has turned into a giant quarantine station, were attempting to take the edge off their ordeal.

They posted photos of their meals, tackled sudoku puzzles and played hopscotch during brief and restricted forays on to the deck. They shared encouraging messages from weary crew members who have kept them fed and entertained throughout a quarantine that Japanese authorities insist will come to an end next Wednesday. Outside, a steel band, hula dancers and jet skiers provided a welcome contrast to health officials in hazmat suits and rows of ambulances waiting to take infected passengers to hospital.

Some said they were simply bored of life in floating limbo, while others broke their silence to voice fears for their health. As Japanese health authorities revealed another 44 infections, Sonali Thakkar, a security officer on the Diamond Princess, was in isolation fearing she could be among the next batch of cases.

“All we want is to be safe and to have more doctors on board,” said Thakkar, who was awaiting the results of her test after developing a fever and cough.

The ship security officer was present on the gangway when passengers who tested positive disembarked in Yokohama to be taken to hospital. While guests have remained largely confined to their cabins, members of staff have been eating and working together, sharing bathrooms and sleeping two to a cabin because of space restrictions.

“All of my colleagues, including the captain, have been very helpful. We’re supporting and taking care of each other,” said Thakkar, 24. “All I want is to get through the next few days. But the rapid increase in cases is definitely not helping us. We’re trying to keep our spirits up, but the fear factor increases as each day passes. My family are praying day and night for me to get home safe.”

Facebook Twitter Pinterest A passenger on the Diamond Princess shows off a teddy bear from her balcony. Photograph: Franck Robichon/EPA

The discovery early last week that 10 people onboard were found to be carrying the virus came as a shock to the Diamond Princess’s 2,666 passengers and 1,045 crew. And then the positive diagnoses kept coming, not by the handful, but in their dozens.

By Friday, 218 passengers and crew had shown positive results among just over 700 who had been tested, along with a Japanese quarantine officer who conducted preliminary health checks just before the ship went into lockdown. The ship’s once carefree community, who until two weeks ago were making calls at ports across the far east, is now host to the biggest single cluster of coronavirus cases outside China – and by some margin.

The leap in positive diagnoses has raised questions about the Japanese government’s decision to keep everyone onboard after it was revealed a previous passenger had tested positive in Hong Kong at the end of last month.

There has also been criticism of the slow pace of testing, although officials have said they hope to increase the number of daily tests from 300 to 1,000.

“On the ship, infections are getting very dense … it now provides a favourable environment for the virus to spread and I think it’s time for people to get off,” said Shigeru Omi, an infectious disease prevention expert and former regional director for the World Health Organization. “It is like we are seeing a very condensed version of what could happen in a local community.”

But Jennie Wilson, a professor of healthcare epidemiology at the University of West London, said confining passengers to their rooms was not much different from moving them to accommodation on land. “The more you move people about the more contact they have with other people outside the groups and the greater the potential to spread to new contacts,” she said.

Play Video 1:46 Coronavirus: Briton tells of life on quarantined cruise ship – video

Wilson said it was likely that people had been infected before the passengers were placed in isolation and the first 10 cases diagnosed. “Those 10 people had been wandering about the ship for a week before any quarantine started. That means that other passengers were exposed to the virus during this time, so you would expect new cases to keep coming up for at least 14 days after the quarantine started.”

Passengers have become their own cabin staff, changing sheets, doing laundry and cleaning toilets. Some have staved off boredom by playing games, bingeing box sets and movies, practicing tai chi and going online.

Virginia Lau (@virginiaylau) Day 3 of quarantine on the Diamond Princess cruise ship in Japan:

- More confirmed #coronavirus cases

- Aunt and uncle are given gloves and thermometers 🌡

- Uncle does tai chi with 🎵 #クルーズ船 #CoronavirusOutbreak pic.twitter.com/FpX0XGJK7s

Momentary relief comes three times a day with a knock at the door by staff in gloves and masks serving meals, making sure not to set foot inside cabins. As David Abel, a British passenger, said last week, this is no longer a holiday but a test of endurance.

Passengers in their 80s and 90s, those with pre-existing health conditions or who have been staying in windowless cabins were preparing to disembark on Friday after health officials accepted that being confined to their cabins with only occasional periods on the open deck could pose a bigger threat to their health. Officials said 11 people had left, but declined to say whether more would depart on Friday.

“The hardest part is the unknown of what is going to happen and trying to stay busy,” said Kent Frasure, an American onboard the cruise liner. “Boredom is a real thing, and it is getting more difficult to stave off, but so far so good.”

Frasure was among those spending Valentine’s Day alone after his wife, Rebecca, tested positive and was placed in isolation in hospital. But he is making plans for after their ordeal ends. “If we are forced to stay a few days then something like going to Tokyo Disneyland might be on the table. Once we get home, a nice pizza is high on the list!”

On Friday, some passengers were able to send messages to loved ones via smartphones – a gift from the Japanese government. There were also displays of affection for the Princess Diamond crew, who were greeted by cutout paper hearts stuck to the door of one woman’s cabin. “Thank you for all your hard work,” read the message on one. And on another: “Thank you for taking care of us.”