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.
More top news
Here is your Tuesday morning weather forecast with Helen Plint.
Your Tuesday morning weather forecast with Helen Plint.
Twin boys with a rare genetic condition have defied the odds after becoming the UK's first twin transplant patients.