The Lake Cote aerial photo
The account
An automatic mapping camera belonging to the Costa Rican government supposedly caught a metallic disc over the lake, and no one aboard saw a thing.
What investigators found
Analyses found no tampering on the negative, but the object remains unidentified; skeptics point to a film defect or a reflection as possibilities.
The story
On September 4, 1971, an Aero Commander twin-engine plane from Costa Rica's National Geographic Institute was flying a routine aerial survey near Lake Cote. The automatic camera fired off photos in sequence for mapping, under the responsibility of photographer Sergio Loaiza. Only when the film was developed did a disc-shaped object appear, in a single frame, near the surface of the lake, absent from the photos taken before and after.
The image spent decades under examination by ufologists and photo analysts, among them Richard Haines and Jacques Vallée, who found no signs of fraud on the original negative. That is why it is regarded as one of the most studied UFO photos in the world. The open question is what was photographed: a film defect, a reflection, an ordinary object out of scale, or something still unexplained.