it's known as the 'Blue Lagoon', but the flooded former quarry near Buxton hides a toxic secret.
It's so polluted that it's almost as toxic as bleach.
There are warning signs that state the water can cause skin and eye irritations and stomach problems, but people continue to swim there.
More top news
Find out how long the cold snap will last
Commuters are being warned to plan ahead and expect disruption on Friday as staff on Northern rail services hold a one-day strike.
Tributes have been paid to a four-year-old boy from Cheshire who died while on a family holiday to Egypt.