"An underwater landslide off the Cornish coast has caused "bizarre" conditions including tsunami waves and static in the air across the south of the UK.
Witnesses said the sudden movement around 200 miles out to sea caused the tide to suddenly shift by 50 metres, creating walls of water.
The change in air pressure also generated static that left onlookers' hair standing on end in the extraordinary environmental events earlier today.
There were even reports that the conditions caused fish to leap out of the water.
Experts said the phenomenon, which was felt from Penzance in Cornwall to Portsmouth, was likely to have been caused by a landslide on the continental shelf under the sea.
Simon Evans, 45, who was digging for bait on the beach at Marazion in Cornwall, said: "It was really eerie, like nothing I've ever experienced.
"The weather was really foggy but extremely warm and close and the sea was as calm as a mill pond.
"One minute I was literally stood at the water's edge, then when I turned around the water had retreated around 50 yards.
"It was surreal and I couldn't believe what had happened. I had no idea what had caused it, but I didn't really want to hang about and find out.
"The only time I'd ever heard of anything like it was hearing about tsunamis so I jumped in my car and got out of there."
Tourists visiting St Michael's Mount in Cornwall were also caught up in the events as a metre-high wave surged up rivers.
Bob Hunt, head guide at the National Trust site, said: "One minute they were happily walking across the walk way and the next they were knee deep in water. It was bizarre.
"I'm not sure what caused it but everyone's hair suddenly stood on end. It felt as though there was suddenly lots of static in the air."
"The sudden change was so strong there were two walls of water, with the eastern side around 8 inches higher than the other."
Bob Brown, who was launching his dinghy at the time said a landowner had seen "lots of fish jumping out of the water."
The Tidal Gauge Anomaly recorded higher tides than forecasted in Newlyn, Plymouth and Portsmouth.
Dr Martin Davidson, coastal processes expert at the University of Plymouth, said the wave was probably caused by a sand or mud slide at sea.
He said: "They are quite rare and it was probably not a tidal phenomenon but more likely a tsunami of some kind.
"It was probably not due to an earthquake, which is the normal cause of a tsunami. This one was probably more likely to have been caused by a landslide."
The Met Office said there was no evidence of weather variations and The British Geological Survey said there was no seismic activity in UK waters over the weekend."