A man showing his family around his new home in Gwynedd found an unexploded bomb in his kitchen cupboard.
Henry Southall, 24, and his parents were exploring the seaside property at Porthmadog when they discovered the device from World War II.
He says an Army bomb disposal team told him it contained 16lbs of explosives.
They discharged it on a nearby beach which people heard from two miles (3.2km) away, according to Mr Southall who runs a tea room at the resort.
"It left a crater in the sand," he said.
The drama started after Mr Southall opened a cupboard in the corner of his kitchen and found the device gathering dust.
He is now trying to find the previous owner to ask how it came to be at the property.
"I'm glad I found it when I did," he said.
"I wouldn't have wanted it going off while I was in bed upstairs."