In 1944, less than a year before the end of World War II, the US and New Zealand began testing an underwater "tsunami bomb" designed to wipe out coastal cities with massive, 30-foot tidal waves. The top secret operation, code-named "Project Seal," is detailed in a new book called Secrets and Treasures from New Zealand-based filmmaker Ray Waru, who learned of the project while digging through military archives. All told, some 3,700 bombs were detonated before the project was shelved in 1945, though its mere existence raises some fascinating counterfactuals. "Presumably if the atomic bomb had not worked as well as it did, we might have been tsunami-ing people," Waru told the Telegraph. "It was absolutely astonishing."