A man has died and two teenagers are missing in separate incidents after they went swimming in the hot weather.
Thames Valley Police said they responded to reports of a man in the Jubilee River in Slough and a body was recovered, with man pronounced dead at the scene.
The death is not being treated as suspicious and the man's next of kin have been informed.
In separate incidents, two search operations are under way in Warwickshire and Essex to find teenage boys who went missing after swimming as temperatures soared during the heatwave.
The coastguard was called at 6.20pm on Thursday to reports two boys were in difficulty near Clacton Pier, Essex.
One boy was rescued by a lifeboat crew and has been given the all-clear by medics, but the other teenager has not been found.
A search has also been launched for a 17-year-old boy who went missing while swimming at a former quarry.
The alarm was raised at Bishop Bowl Lakes near the village of Bishop Itchington in Warwickshire just after 6.30pm on Thursday.
It is believed the teenager got into difficulties while swimming.
Specialist water rescue teams, fire and ambulance are in the area and thorough searches are being conducted.
Inspector Rupert Atkinson said: "We continue to search the area with specialist teams and the support of a number of partners.
"There is a lot of speculation on social media and we would ask that people respect the family's privacy.
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"We would also encourage anyone who was in the area at the time to come forward. Any information, no matter how small it may seem, could be pivotal as we continue our search."
The Local Government Association, which represents 370 councils in England and Wales, issued water safety advice this week after several people drowned while swimming during the hot spell.