The Maury Island Incident (1947)
On 21 June 1947, three days before Kenneth Arnold’s sighting, Harold Dahl claimed he had seen six ring-shaped objects above Puget Sound, Washington State. One of them was said to have dropped a shower of hot slag onto his boat, killing his dog and injuring his son. The next morning, he said, a man in a dark suit approached him in a café and advised him to keep quiet.
Witnesses
2 harbour patrol boatmen
Why it endures
This is where the figure of the "man in black" first appears, later a central motif of UFO culture. The affair also cost the lives of two Air Force investigators whose bomber crashed while carrying samples back, which fed decades of suspicion.
Official version (contested)
The Air Force and the FBI concluded it was a fabrication: the slag was ordinary smelter waste, and investigator Edward Ruppelt filed the whole affair as a hoax staged to sell magazine articles. Researchers dispute that Dahl ever confessed, and the FBI agent on the case himself judged that it was the confession of a hoax that had been fabricated.