People defied lockdown warnings to swim in lagoon's water dubbed the "most dangerous in the UK" by a police chief.
Locals flocked to Harpur Hill lagoon in Buxton, Derbyshire, known locally as the Blue Lagoon, as bank holiday temperatures soared, despite warnings that it is a toxic dump.
The PH chemical value in the water makes it similar to swimming in “a bath of bleach”, DerbyshireLive reports.
It is also said to be filled with old cars, animal carcasses and faeces, but residents continue to travel to Harpur Hill to swim in the water.
Danielle, 22 from Sheffield, said: "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 was criticised for pouring black dye into the water to deter visitors.
The lake water is dyed black each year in an effort to make the site look less appealing to visitors.
Derbyshire Fire and Rescue Service put a post on Twitter saying: “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!"
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.”