Hiker films 20-metre deep sinkhole as it suddenly appears in field

A man witnessed a giant sinkhole appear in the middle of a field, while he was on a hike. In a short video clip, the walker edges towards the mysterious hole and appears to be shocked by the depth - an estimated 20m. The sinkhole arose from the collapse of the soil in an area with underground rivers, in Lingenfeld, Germany.

What is a sinkhole?

A sinkhole is a depression or cavity caused by collapse of the surface layer due to loss of support from below. It usually takes a number of years for a void below the surface layer to form, but in some cases it can happen rapidly. Surface layers can form a bridge that makes it impossible to tell there is a void beneath, but a trigger event - such as heavy rainfall or a change in surface drainage - will eventually lead to collapse.