It was not until 2010 that anyone thought to open the heavy steel hatch, climb down the ladder and explore the 8-foot-by-10-foot chamber that the home's previous owner had built to protect his family from a nuclear attack.

Floating in five feet of water that had seemed into the bunker were sealed U.S. Army boxed packed with all of the supplies a family would need to survive two weeks underground.

'We assumed it was just this empty space,' homeowner Carol Hollar-Zwick told the Appleton Post-Crescent.

The boxes, old military ammunition crates, contained markings that suggested there might be explosives inside, so the family called the local branch of the Bureau of Alcohol, Tobacco and Firearms.