Americans leave quarantined Japan ship as virus cases hit 355 Images show the Diamond Princess vessel at port in Yokohama as American tourists prepare to leave the quarantined cruise ship to board chartered flights home as the number of new coronavirus cases diagnosed on the vessel jumped to 355. The Diamond Princess was placed in a 14-day quarantine in early February after a former passenger tested positive for the virus. Americans on board were given the option to leave the ship and fly home, where they will face another 14-day isolation period. IMAGES