USOs-Unidentified Submerged Objects
The flying saucers of the sea
While the image isn’t exactly what I was looking for because this isn’t a USO, it shows two things. One that free images for such subjects are extremely limited, and two that the U.S. government has known more and for longer than they have let on.
In 1970, biologist Ivan Sanderson published a book entitled Invisible Residents…