There is a warning for families tonight after hundreds of people have been putting themselves at risk by swimming in toxic water in Derbyshire.
The blue lagoon near Buxton is actually a flooded quarry.
The water there looks similar to the clear blue seas you might expect to find in an exotic foreign location but that is because it contains limestone.
Environmental experts say the water causes skin and eye irritations as well as stomach problems, but families and young swimmers keep on coming. Our correspondent, Matt O'Donoghue, reports
The Blue Lagoon near Buxton, a flooded quarry - has inviting turquoise waters, but it is so polluted it's almost as toxic as bleach.
There are warning signs saying it can cause skin and eye irritations and stomach problems, but families and young swimmers are ignoring them.
Councillor Pam Reddy says the water is so toxic in the lagoon that she wouldn't swim in it even if she was paid to.
Dr. Tim Clayton, Consultant Dermatologist talks about the health risks the polluted water could cause if it came into contact with skin or was swallowed.
Local resident Phil Baker says he's tried to put up warning signs about the toxic lagoon water but says people aren't' paying attention.