A former NASA researcher believes pilots of UFOs could be living underneath our oceans.

Kevin Knuth, a distinguished academic who worked at NASA's Ames Research Center from 2001 to 2005, thinks there are many reasons why alien visitors might choose to base themselves underwater, rather than on the Earth’s surface.

For a start, he says, if they prefer to remain undetected, the deep oceans are ideal. He told the Theories of Everything podcast: “75% of the Earth's surface is water and we really have very little access to it. So, if you are going to hide out somewhere, that's perfect.”

Many recent UFO sightings have involved craft that appear to move effortlessly between the air and sea, and Kevin adds that aliens from a water-world home planet would have many reasons to base themselves beneath the sea.

To read more, click here.