Teddington Lifeboat Station is warning swimmers not to go into the Thames after a body was recovered near Kingston on Wednesday.
Along with other similar organisations, it has been running a campaign using the hashtag #RespectTheWater to prevent people from swimming in the river.
The biggest risk is ‘cold water shock’, where the blood supply is cut off to the muscles which prevents them from working, which can lead to hypothermia, and even cardiac arrest.
Teddington Lifeboat Station helm Jon Chapman said: “Don’t be tempted by the water. Go to a lifeguarded pool, go down to a lifeguarded beach.
“If you’re doing anything on the Thames, you should do it with proper supervision and knowledge.
“In other words, get some expert advice on it, know the dangers, know the issues involved, and keep yourself safe.”
Swimming hotspots in the area include Twickenham riverside, Teddington Lock, and Kingston Riverside.
The Metropolitan police said the body of a man was recovered from the Thames on Wednesday at around 4:30pm, and is believed to be a man, aged 47, who entered the water to swim and did not resurface.
Three bodies have been recovered from the Thames across London after unsuspecting swimmers have jumped in to cool off in the hot weather, including the body of a 23-year-old man in the Shadwell Basin, East London.
Inspector Stuart Simpson from the Met Marine Policing Unit said: “Anyone who sees or hears anyone who may be planning on entering is asked to speak to them and attempt to talk them back to a safe piece of land.
“You should not put yourself in any danger. If you do see a person in the water, then you should call 999 and ask for the coastguard and police.”