IT is a bizarre phenomenon that makes the ground become more like jelly.
Now a video has captured the moment that the ground started to wobble beneath a pair of dog walker's feet in a Hampshire field.
The video shows the ground rippling and bulging underneath a pair of dog walkers as they ventured across a waterlogged field in the New Forest.
Nick and Beth Minister were walking their dog Molly when they felt the earth move beneath them, and with them to capture the moment it happened was Ben Havers - he described the mud as a 'magic carpet'.
He said: “We just happened upon it, there were several similar patches to this one. This was the first one we came across. It was about 10ft sq in area.”
One part of the video shows muddy water bubbling out of a hole after Mr Minister pierced the ground with a stick - the group likened this to a giant pimple.
Mr Havers added: “It's very clay heavy ground around there so we were quite confident it was a shallow recess and not a deep 'sinkhole' underneath.”
Senior Tree Officer at the New Forest National Park Authority Bryan Wilson explained the 'wobbly effect'.
He said: “It is not an uncommon occurrence in the New Forest in times of heavy rainfall. What the reason is that you have an impermeable level of soil that the water cannot penetrate, so when you get this unprecedented level of rain fall you get water building up to the surface.
“On the surface you have a growing layer of grass within about two or three inches of soil, and underneath that you have this layer of water so it is like walking on a waterbed.”
Bryan has worked in the New Forest for more than 25 years.
He added: “You will find it across various spots of the Forest during the winter time, but what is different about this is the levels of rain are covering bigger areas of ground. I have never seen anything like this being so widespread like it is now.”
He also warned that people should not do what the dog walkers in the video did and walk across the wobbly areas.