Horrifying footage shows thousands of gallons of water contaminated by raw sewage flowing into the sea - just metres from where children swim.
A surfer captured the shocking video, which shows the popular and secluded Trevaunance Cove, in St. Agnes, Cornwall.
Usually the waters are a stunning turquoise blue and are revered by locals and tourists alike.
This spot was even a well-visited spot during the half-term holiday and saw children enjoy a last splash before the winter months.
However, the waters have now turned a murky brown, with the sludgy flow seeping out into the cove and for yards out - with Cornish surfers and the Green Party now emphasising that the water did contain human excrement.
The videographer, who wishes to remain anonymous, beings the video by panning around to show the scale of the sewage problem - which runs hundreds of feet into the sea.
As the clip continues, parts of the tranquil waters can be seen merged together with the sludge, creating a clear divide between the two.
Speaking about the disgusting state of the sea, the surfer said: "Sadly the events in the video are on the increase, happening more often with less rainfall, rather than reducing.
"As a regular water user I can testify to this. It did improve in the late 90s/early 2000s after pressure from organisations such Surfers Against Sewage.
"But it has been on the increase again over the last five to 10 years.
"Sadly, this is becoming an increasingly common occurrence, not just here, but all around the country's coastline and rivers."
This particular incident, on Sunday morning (October 30), was just one of several sewage warnings issued that day, with environmental charity surfers Against Sewage (SAS) warning against storm sewage at Trevaunance Cove, but also at Mawgan Porth, Fistral North, Crantock, Godrevy Towans and Gwithian Beach.
The pollution alerts over the weekend read: "Storm sewage has been discharged from a sewer overflow in this location within the past 48 hours."
Karen La Borde, a Truro City Councillor and the Green Party’s parliamentary candidate for Truro and Falmouth, has now been left concerned by the video, saying: “Cherilyn Mackrory MP has echoed South West Water’s claim that this was mostly storm water, but local surfers report that there was plenty of all too recognisable human excrement in the mix.
"This is a real danger to human health, as well as harming the marine environment and Cornwall’s reputation as a holiday destination."
Meanwhile, Joel Henthorn, chair of St Agnes Surf Lifesaving Club, told the BBC that the water off Trevaunance Cove was "grey and frothing and smelled of sewage", adding that there were toilet roll remains flowing on to the beach and the smell was "horrible" and "unbearable".
Speaking about this issue, a South West Water spokesperson said: "While the storm overflow at St Agnes triggered briefly on Sunday (October 30) following heavy rain, this was a short duration spill and is unlikely to have caused the level of discolouration shown in the video.
"On this occasion, we believe there were other factors which contributed to the discolouration, such as mud in the water dislodged by the heavy rain flowing into the area from a nearby stream and runoff from agricultural land.
"We continue to increase investment in the region's infrastructure as part of our ongoing commitment to protecting and enhancing the natural environment."
They then went on to explain: "This year the South West has seen the dramatic changes in weather patterns presented by climate change, as demonstrated in August when the region was declared in drought.
"Through these changes we are now experiencing more extreme weather patterns than ever before and this year the South West saw one of the driest and hottest years on record.
"As well as prolonged periods of extremely hot weather, we have seen heavy localised rainfall which hasn't been able to permeate into the dry ground, meaning significant volumes run into our network, which can cause our storm overflows to trigger."
