"Multiple negative PCR tests were required before the guests boarded, but this was not sufficient to prevent Covid-19 onboard," the company said in a statement released Tuesday.
A total of 7 guests and two crew members aboard SeaDream 1 tested positive for Covid-19, the statement said.
The ship embarked from Barbados on November 7 on a sailing that was meant to show that regular testing aboard the ship and other safety protocols could allow cruise voyages to take place safely during the pandemic.
SeaDream 1 was the first cruise vessel to resume sailing in the Caribbean after the pandemic shut down operations in March.
SeaDream noted that it operated 20 sailings during the pandemic without any cases and it made additional improvements to safety protocols before it launched the first of what was supposed to be a series of sailings from Barbados this winter.
"The company will now spend time to evaluate and see if it is possible to operate and have a high degree of certainty of not getting Covid," the statement reads.
Passenger Gene Sloan took this photo during the cruise that's been cut short by a Covid-19 outbreak.
Gene Sloan/The Points Guy
'How often and how big?'
After a passenger received a preliminary positive test result on November 11, the ship returned to Barbados to test all passengers and crew.
The passengers who tested negative for coronavirus began to disembark the SeaDream 1 cruise ship to fly home Saturday, according to passenger Ben Hewitt.
Five passengers who tested positive also disembarked for a private flight back to the United States, according to Hewitt.
Hewitt, host of Cruise with Ben & David on YouTube, was among a handful of cruise journalists and bloggers on board the SeaDream Yacht Club cruise. Gene Sloan, a senior reporter for cruise and travel at The Points Guy, was also on board.
Passengers were tested in advance of traveling to the ship and also before boarding the ship, Sloan said.
"I think what this shows is it's going to happen. And until there's a vaccine or herd immunity, when cruising starts up you're going to see things like this happen. The question is how often and how big?"
Fewer than 250 guests
SeaDream's ships, which the company refers to as "superyachts," have capacity for 112 guests and 95 crew.
Carrying fewer than 250 guests outside of US waters allows SeaDream to operate outside of the US Centers for Disease Control and Prevention's orders around cruising.
The CDC recently issued a "Framework for Conditional Sailing Order for Cruise Ships."
The order is considered a tentative step toward the resumption of cruising.