During World War II, the Nazi’s pillaged all the metals they could to fuel their munitions plants, from anyone and anywhere. Gin distilleries were no exception, and they had valuable copper to boot.
Filliers, a Belgian gin distiller, had other plans. They had gin to make, so protecting their stills was priority #1. But what to do when the Nazi’s are coming your way? Why, hide everything underwater of course! And that’s what they did — hid their copper in nearby lakes for protection.