On August 17, 1963, 10 kilometers away from the Naha coast, the Naha Tomari-Kume Island ferry "Midori Maru" sank due to severe sea conditions. Unable to transmit a distress signal, a sailor swam to give alert but the rescue was too late. Out of 242 passengers, 112 died in what was the worst accident in Okinawa's maritime history.