A 14-year-old boy has died after entering the River Thames on Monday, the Metropolitan Police said.The teenager went into the water near Millwall Outer Dock, on London’s Isle of Dogs.The London Fire Brigade and the Met were alerted about 6.50pm on Monday.The boy’s body was recovered around 10.30pm and he was pronounced dead at the scene.The Met’s Detective Superintendent Oliver Richter said: "Our thoughts remain with the family and loved ones of this young boy at this incredibly difficult time. “As the warm weather continues, I would urge everyone to remember that open water can present serious dangers."Pickmere Lake, where a 17-year-old boy drowned earlier this summer (Getty/iStock)Mr Richter urged people to only swim in designated areas, and to take the time to speak with children and young people about staying safe around water.The boy’s death is being treated as unexpected but not suspicious.Police said inquiries continue to prepare a report for the coroner.London Fire Brigade Assistant Commissioner Patrick Goulbourne said: “Sadly, a teenager has drowned following an incident in Blackwall.“Firefighters responded to reports of a teenager in the harbour and carried out a full search of the area. Sadly, despite the best efforts of emergency responders, the teenager was later found dead.”There have been multiple heatwaves across the UK this summer (AFP/Getty)There have been more than 100 accidental drownings in London in the past six years.At least 15 people have died in open water this summer during prolonged hot weather across the UK.The Royal Life Saving Society urged people to “stop and think” before getting into the water in response to the deaths, most of whom were children.The UK Health Security Agency (UKHSA) has warned of the increased risk of cold water shock, which is the body’s natural physical reaction to sudden immersion in cold water.The response is immediate and can lead to drowning, the National Fire Chiefs Council (NFCC) said. Anyone who suddenly enters cold water is at risk, especially if they accidentally fall in or jump in. Experts warn that cold water shock can affect anyone, regardless of swimming ability.Subscribe here to get the latest updates from The Independent.