A Cold War hydrophone network built to track Soviet submarines across entire ocean basins was declassified in 1991, and scientists now use those same undersea microphones to follow individual whales calling to each other across thousands of miles of ope - Space Daily

Christopher Clark, the marine mammal scientist who ended up running the civilian side of this network, has said it plainly: “I could show you the evidence today. I can listen in Puerto Rico to a whal…