An expedition ship departed on an Antarctic cruise mid-March 2020 with no known COVID passengers or crew members. However after 8 days the first passenger became febrile and isolation procedures were followed. A further 24 members of the ship developed symptoms (some as late as 23 days later) with 8 requiring medical evacuation. Of the 217 passengers and crew on board, 128 tested positive for COVID-19 with 81% of those positive being asymptomatic. This paper demonstrates how quickly COVID-19 can spread as well as the high number of COVID positive people being asymptomatic showcasing the importance of testing in this group.