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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Pollen: West Midlands Latest Update
Pollen: East Midlands Latest Update
After a dry evening, rain will arrive overnight. Brighter tomorrow.