> “Periodically when caverns are empty you can actually shoot sonar images of the caverns,” says Corbin. “And that gives you a three-dimensional way of looking

> “Periodically when caverns are empty you can actually shoot sonar images of the caverns,” says Corbin. “And that gives you a three-dimensional way of looking at them.” Some have interesting shapes, he adds. The outline of one chamber, for example, would resemble a large flying saucer. Mm yes this is a conspiracy theory waiting to happen