The family of a "kind and loving" 13-year-old boy who died after getting into difficulty while swimming in a Northumberland river say they are "absolutely devastated".
Robert Hattersley, from Crawcrook, lost his life following an incident in the River Tyne near Ovingham on Sunday.
His family said in a statement: "It is impossible to put into words the heartbreak we are feeling - Robert was so kind and loving. We are absolutely devastated by what has happened.
"He brought a smile to so many people's faces and he will be missed by absolutely everyone who knew and loved him."
Detective Inspector Phil Hughes, of Leeds CID, said: "This incident serves as a timely reminder about the dangers of swimming in open water."
Meanwhile, a 16-year-old boy became the fourth person to drown in open water during the current heatwave as Britain swelters and temperature records could be broken.
The teenager died after getting into difficulty earlier today in Bray Lake, near Maidenhead, in Berkshire.
Thames Valley Police said officers were called at 11.45am to the site and a search of the water was carried out by the force as well as other emergency services, including fire crews.
The boy was found just after 1.30pm and died at the scene.
Superintendent Michael Greenwood, the local policing area commander for Windsor and Maidenhead, said it was an "absolute tragedy".
Emergency services have issued urgent appeals for people to stay out of dangerous waterways and reservoirs.
A 50-year-old man lost his life after getting into difficulty at Ardsley Reservoir, between Leeds and Wakefield. A body, thought to be his, was found on Sunday.
A 16-year-old boy died after he was seen struggling in the water at Salford Quays, Greater Manchester, on Saturday.
Met Office forecasters issued a red warning for Monday and Tuesday in an indication that temperatures could push above 40C (104F).
The existing UK record, of 38.7C (101.66F), recorded in Cambridge in 2019, looks almost certain to fall.
Temperatures rose to 38.1C (100.58F) in Santon Downham, Suffolk today, making it the hottest day of the year, and the mercury topped 37C in a number of other places.
Wales has provisionally recorded its hottest day on record, with the temperature reaching 37.1C in Hawarden, Flintshire, beating the previous record for the country - 35.2C - which was also set in Hawarden, in 1990.
Tuesday is predicted to be even hotter in the UK, with temperatures possibly reaching a "crazy" 41C (105.8F) in Yorkshire and Lincolnshire.
On Sunday Tracy Nicholls, chief executive of the College of Paramedics, warned the "ferocious heat" the UK is predicted to experience over the next few days could lead to deaths.
She told Sky News's Sophy Ridge On Sunday programme: "This isn't like a lovely hot day where we can put a bit of sunscreen on, go out and enjoy a swim and a meal outside.
"This is serious heat that could actually, ultimately, end in people's deaths because it is so ferocious. We're just not set up for that sort of heat in this country."
The UK Health Security Agency raised its heat health warning to Level 4 - a "national emergency" - on Friday.
Level 4 is reached when "a heatwave is so severe and/or prolonged that its effects extend outside the health and social care system".