Alarming pictures show swimmers taking a dip in "the most dangerous waters in the UK".
People have been warned to stay out of the toxic electric blue water in Buxton, Derbyshire.
But yesterday people were spotted diving into the former quarry, known locally as the Blue Lagoon, Derbyshire Live reports.
It's believed that people travelled from Staffordshire nad Yorkshire to the site on the edge of the Peak District.
However, anyone planning to go to the Blue Lagoon is being warned it is like having a 'bath in bleach' due to the PH level.
There are also old cars, animal carcasses and faeces in the water.
And Derbyshire’s Chief Constable has described the pool as 'probably the most dangerous water in the UK'.
Now people are being reminded to stay away over half-term.
Danielle, aged 22, from Sheffield, told DerbyshireLive : "My family has been coming here for years so I thought it would be busy but I didn't expect it to be this busy to be fair.
"We've just come down with the kids for a picnic but I don't think we'll stop for long. I can't believe how busy it is.
"I'm amazed people are swimming. The signs make it obvious how dangerous it is."
Earlier this year, Derbyshire Police faced criticism for for pouring black dye into the water to deter visitors.
Lord Sumption even called it 'disgraceful', saying: “This is what a police state is like, it is a state in which a government can issue orders or express preferences with no legal authority and the police will enforce ministers’ wishes."
The lake is, in fact, dyed black every year in an effort to make the site look less appealing to visitors, as the water is otherwise a lovely crystal blue colour.
A Derbyshire Fire and Rescue Service spokesman said: “We’re aware of people continuing to visit Harpur Hill quarry, known locally as the Blue Lagoon.
“Did you know it gets its blue colour from toxic deposits seeping from the quarry stone and is the same PH value as bleach!
“Would you swim there? #StayAway.”
Derbyshire’s Chief Constable Peter Goodman previously said: “That area was a quarry near Buxton and the water in there looks like a very attractive blue because it is full of chemicals.
“It looks attractive, so lots of people go there.
“But it is probably the most dangerous water in the UK, experts say.
“It is highly alkaline and is full of chemicals. It is like going for a bath in bleach.
“Every year we have been trying to make it look less attractive so people won’t go there. It is not that coronavirus that has done this, we do it every year.”
