At least 15 people drowned in open water in the UK’s recent heatwave, mostly children and teenagers. The public response is understandably urgent: warnings are issued, parents are told to talk to their children, and young people are reminded that rivers, lakes, reservoirs and canals can be dangerous. Those warnings matter. Open water can be risky, especially when the air is hot but the water remains cold. Hidden currents, submerged hazards and cold-water shock can all turn a moment of relief int