Allegedly, on the evening of August 11, 1945, a number of ancient ships, junks and fishing boats were anchored near a small inlet by the Japanese. Just before dawn on August 12, a remote controlled launch carrying the bomb slowly made its way through the assembled fleet and beached itself.

Nearly twenty miles away, observers wearing welders' glasses were blinded by the bomb's terrific blast. "The ball of fire was estimated to be 1,000 yards in diameter. A multicolored cloud of vapors boiled towards the heavens then mushroomed in the stratosphere. The churn of water and vapor obscured the vessels directly under the burst. Ships and junks on the fringe burned fiercely at anchor. When the atmosphere cleared slightly the observers could detect several vessels had vanished."

Found via The Marmot.