The structure, estimated as being between 3.5 and 11 miles across, was spotted on Google Earth in the Pacific Ocean just west of Mexico.
A video about the discovery uploaded to YouTube has drawn vast speculation about what it could be, including an ancient sunken city, a bizarre UFO, or even an alien base.
The “discovery” was made by Argentinian Marcelo Igazusta.
The video commentary described it has being “an intense light in the Pacific Ocean” of 3.5 miles in length, with a shape similar to a plane.
Scott C Waring, an alien conspiracy theorist, said: “It is a perfect pyramid that measures over 8.5 miles across one side of its base. Thats a conservative estimate, it could be up to 11 miles across.” (Read more from “8-Mile Pyramid Discovered at Bottom of Ocean” HERE)