The Centers for Disease Control and Prevention (CDC) has reported that 68 cruise ships run by lines like Carnival and Royal Caribbean have met the agency’s “investigation threshold” for crew or passenger COVID-19 outbreaks, or have had a health department official alert the agency of positive cases in passengers within five days of disembarking. Thirty-six cruise ships are under ongoing investigation, while 32 others have undergone investigation already and are now under “observation.” A CDC spokesperson responded to statements that positive cases occur less at sea than on “land” with a note that the likelihood of transmission is still high in such settings, and that it’s impossible for cruises to be a “zero-risk activity.”