Lago de Cote photograph, Costa Rica
On 4 September 1971 an aerial mapping flight of Costa Rica's National Geographic Institute photographed Lake Cote; one frame shows a disc-shaped object over the water that nobody on board saw.
1971 CE · 10.58, -84.91 · status: disputed
The account
The survey was for a possible hydroelectric project in the Arenal area. Cartographer Sergio Loaiza noticed the object only when the negatives were examined. La Nación published it on 1 November 1979, and it has since been called one of the best UFO photographs ever taken. A documentary on it was released in 2025.
The sceptical view
Because only one frame of a sequence shows the object, a fast bird, a defect or debris on the film, or a reflection remain possible. Analyses were made mainly by UFO researchers, not by an independent scientific body.
The researched reading
One of the better UFO photographs: an official negative, honest provenance and careful analysis. Its weakness is that it is a single frame nobody saw, which leaves a close bird or debris possible; neither side can close the case.
| Explanation | Weight | Why |
|---|---|---|
| Something known, misidentified | 40% | A single frame from an automatic mapping camera, with nothing in the frames before and after, is what a fast nearby object would produce: a bird or a piece of debris close to the aircraft, out of scale and unseen by the crew. A boat wake on the lake was also proposed for part of the image. |
| Genuinely anomalous | 36% | Haines and Vallée’s photo analysis found a sharp-edged, disc-like object below the camera with no sign of film damage, and no conventional candidate matches it well at the estimated range; since the frame interval also rules out a slow object, a real unexplained object keeps a large share. |
| A known natural phenomenon | 6% | Water spray, a dust devil or a cloud fragment could form a bright blob, but the sharp edges reported by analysts fit them poorly. |
| A hoax or fabrication | 6% | The negative came from a government survey roll and was found years later by staff; tampering is unlikely. |
| A poorly understood natural phenomenon | 5% | An unusual atmospheric or film effect not well understood could account for a single-frame image. |
| Secret human technology | 5% | Secret aircraft over a remote Costa Rican lake in 1971 are improbable, and the shape fits no known type. |
| Perception, memory or mind | 2% | Nobody saw anything; the evidence is the film itself. |
Official position: No official finding by the Costa Rican institute; the photo was analysed mainly by UFO researchers (Haines and Vallée), who reached no conventional explanation.