A peculiar bubbling in the sea is proving a mystery to coastal visitors unsure of its cause.

A video of the strange motion in the water off Folkestone was captured by passerby Jamie Clarke, who shared the footage online in a bid to find out what it could be.

Mr Clarke, who has lived in the town his whole life, says he has never noticed anything like it before.

He said: “I am not sure what’s causing it.

“I know the sewage pipe does run out to sea but I thought that was further along at Copt Point.

“But thinking about it, there must be a pipe running along from the sewage works at the Sunny Sands.”

Mr Clarke’s post has sparked speculation about the cause of the mystery bubbling.

Some believe it is linked to a sewage pipe, while others say it has “been there for years”.

“That's naughty – not sure it's safe swimming near that,” wrote Chris Young.

Ralph Thorogood speculated: “It’s a hole in the sewer pipe.”

Russell Reilly also backed this idea, adding: “It’s air pressure from the old pipes on the beach, nothing to worry about.”