People have been spotted swimming in a toxic poo-riddled pool that is like "a bath of bleach". Derbyshire Police have previously branded the Blue Lagoon as "probably the most dangerous water in the UK".
It is also home to carcasses, old cars and poo. And its PH value is what makes it feel like swimming in a "bath of bleach". But that didn't stop some people swimming in the Harpur Hill spot to enjoy Bank Holiday Monday's warm weather.
Danielle, 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.