The photo above (cropped and enlarged) was taken by a Costa Rican government mapping plane during an aerial mapping mission. This UFO photograph is unique for several reasons. 1) The photograph was taken by a high-quality, professional camera. 2) The unidentified object is plainly visible against the uniformly dark background of the lake and appears in sharp focus. 3) The camera was aimed downward and the plane was flying at a known, fixed altitude (10,000 feet), which makes it easy to calculate a maximum size for the object (683 feet).
The plane carried a crew of four; a specialist in aerial photography, a geographer, a topographer, and the pilot. No member of the crew stated that they saw anything unusual during the routine flight.
Much analysis has been undertaken using the original negative, most notably by Dr. Richard F. Haines and Dr. Jacques F. Vallee. It seems safe to assume that it is not a double-exposure or the result of manipulation of the negative. All indications are that this is a photo of a large three-dimensional disk , or shallow cone, [hovering?] above, and possibly partially submerged in Lago de Cote.
Hmmm did the aliens learn to avoid aerial surveys? We have more aerial and satellite imagery now than ever.