A huge sinkhole has opened up in the back garden of a house in Cornwall, south-west England.
It's thought to be at least 90m deep and in an area of the county where a lot of mining used to happen.
It was discovered when experts drilled down the patio after looking at old maps of the area.
Nobody was hurt and both houses nearby were empty.
Take a look at how big the sinkhole is!
Footage courtesy of Mark Thomas