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.
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WARNING GRAPHIC IMAGES: Lionel the cat is recovering after a crossbow nearly half a metre long was removed from his skull.
West Midlands weather: Dull and mild with rain arriving later
East Midlands weather: Generally cloudy, mainly dry