During the second world war, it's claimed, the US and New Zealand tested a 'tsunami bomb', designed to create waves that could flood a city.
Rumors of such weapons have surfaced before: indeed, they're still doing the rounds. Some conspiracy theorists have even suggested that 2011's tsunami in Japan wwas triggered by the US' High Frequency Active Auroral Research Program (HAARP) technology, by broadcasting an ultra-low frequency signal designed to set off an earthquake.
In this case, though, official documents reveal that there's at least some truth in the story.
The claim appears in a new book, Secrets and Treasures, for which author and film maker Ray Waru trawled through thousands of records and objects in the New Zealand National Archives.
Codenamed Project Seal, the tests established that a series of 10 bombs could create a 33-foot wave. Thousands of explosions were carried out in New Caledonia and at Whangaparaoa Peninsula, near Auckland.
The project, he says, was only abandoned when the atomic bomb was completed in 1945.
"Over a period of several months they carried out almost 4,000 test explosions to kind of calibrate the size of the explosions, the number of explosions and the depth of the explosion in the water would need to be in order to create a tsunami effect," Waru tells Australia's ABC.net in an interview.
"They never actually produced a tidal wave. They decided at the end if there were two million kilograms and they were detonated in an array a specific number of kilometres from the shore that they would produce a wave that wave about ten or 12, I think, meters in height and that would have been enough to wash out a shore installation."
According to Waru, while New Zealand provided the location and logistics, it was the US that was behind the project.
"The Americans probably weren't going to do it in the Pacific. They obviously needed a kind of a military establishment that could get behind it so I guess the choice could have been either Australia or New Zealand," says Waru.