Cruise ships were an epidemiological nightmare during the early days of the pandemic—combining prolific international travel with line dancing, endless buffets, and indoor karaoke—and they’ve also been a disaster for the mental health of some of their crew. Separated from families, confined mostly to tiny cabins, with no obvious legal recourse and at times no pay, sailors experienced a more extreme version of the household lockdowns that have sent people tumbling into depression.

It’s a trend Dr. David Cates, of the University of Nebraska Medical Center, calls a “pandemic within the pandemic.” He cites a report by the Centers for Disease Control and Prevention in August that showed a startling 11% of 5,470 adult respondents among the U.S. population had “seriously considered suicide” over a 30-day period this spring, compared with 4.3% in another large survey in 2018 who reported considering suicide during the previous 12 months. “Being stuck on a ship for an indeterminate amount of time, in a small space—that really checks all the boxes,” says Cates, who treated some of the first rescued cruise passengers at UNMC’s national quarantine center. In addition to the estimated 100 or so passengers and crew who died of causes linked to Covid, there have been at least a half-dozen other fatalities among crew members who were trapped at sea. Most of these are suspected suicides.

Interviews with affected crew members and their families suggest that despite assurances from cruise operators that crew were well cared for, their mental health was at times an afterthought. An October 2019 study on the mental well-being of crew, commissioned by a group affiliated with the International Transport Workers’ Federation, the big maritime trade union, found that even before the pandemic about a fifth of mariners surveyed said they had suicidal thoughts.