Believe or Not??!!
While technically a UFO refers to any unidentified flying object, in modern popular culture the term UFO has generally become synonymous with alien spacecraft; however, the term ETV (ExtraTerrestrial Vehicle) is sometimes used to separate this explanation of UFOs from totally earthbound explanations.
This eBook includes video and interactive graphic materials.
(CNN) -- Deep down on the bottom of the Baltic Sea, Swedish treasure hunters think they have made the find of a lifetime.
The problem is, they're not exactly sure what it is they've uncovered.
Out searching for shipwrecks at a secret location between Sweden and Finland, the deep-sea salvage company Ocean Explorer captured an incredible image more than 80 meters below the water's surface.
At first glance, team leader and commercial diver Peter Lindberg joked that his crew had just discovered an unidentified flying object, or UFO.
Table of Contents 1 Extraterrestrial hypothesis 2 Studies 3 Terminology 4 Early history 5 Investigations 6 Identification of UFOs 7 Associated claims 8 Famous hoaxes 9 In popular culture 10 Gallery of UFOs