Four people have died in separate incidents which have prompted fresh warnings over the dangers of swimming in open water.
A 16-year-old boy, from London, and a 41-year-old man, from King's Lynn, died in unrelated incidents at Bawsey Pits, a series of flood quarries in Norfolk.
In Cornwall, a woman died while swimming in the sea and a man died after getting into difficulties while in a river on the Shropshire/North Wales border. Despite the tragedies and dozens of signs warning of the dangers, members of the public could be seen swimming at Bawsey Pits on Wednesday afternoon.
Norman Melton, visiting the lakes from Wisbech, Cambridgeshire, said: "I don't swim here but the conditions seem fine. I think people will carry on as normal."
Police said that people had attempted to swim in the lake even as the rescue attempt was under way. Norfolk Police assistant chief constable Nick Dean said: "People must heed the warning - you don't know what you're going into, you don't know the currents or what underwater obstacles there are."
The man had told his girlfriend he planned to swim about 50 yards (45m) out in one of the flooded quarries towards an island. He was near the shore of the island when he disappeared below the surface. At the same time, police were told of the missing teenager at another lake about half a mile (0.8km) away.
Both were found entangled in reeds about 6ft (2m) below the surface, Norfolk's chief fire officer Nigel Williams said. Hundreds of sunbathers looked on as the search took place and Mr Williams said officers had to prevent members of the public entering the water.
A spokesman for Sibelco, which runs the disused quarry, said it was deeply saddened by the deaths. He added: "Safety is our prime concern and signs are in place to warn against swimming and diving."
West Mercia Police said emergency services were called to a site near the confluence of the Rivers Dee and Ceiriog, near Chirk. The man was airlifted to the Royal Shrewsbury Hospital where he was pronounced dead. He is believed to be 21 and from Shropshire.
A 40-year-old woman, from Saltash, suffered a "medical episode" while swimming at Seaton, near Torpoint. Devon and Cornwall Police said an off-duty officer pulled the woman from the water. She was airlifted to Derriford Hospital in Plymouth, where she was pronounced dead.