The RNLI rushed to rescue two naked swimmers, who were spotted near Borthwick Wharf in Deptford.
London’s Tower RNLI lifeboat crew launched at 3.39am on Thursday, July 2, after the pair were spotted in the River Thames.
Officers aboard a police boat also arrived at the scene, where they spotted two naked people running away from the water and into some bushes.
Shortly after, one of the skinny dippers emerged clothed from the bushes to offer an explanation.
They were warned by the crew of the serious dangers of swimming in the River Thames.
Kevin Maynard, Tower RNLI lifeboat station manager, said: “London may be gripped by a heatwave but swimming in the River Thames is incredibly dangerous and we would strongly advise people not to do so.
“These two skinny dippers were lucky to escape unhurt as they had put themselves in a potentially life or death situation.
“The River Thames in London has very strong currents that can easily sweep you away. Combine this with the high number of obstacles in the river and swimmers can all too easily find themselves dragged under the water.
“There is also the danger of cold water shock. Despite the hot weather, the river water is still very cold and sudden exposure can cause uncontrollable gasping for air which leads to you gulping down water causing a real risk of drowning.
“If you’re suffering from the heat there are better and much safer ways to cool down than putting your life at risk by swimming in the River Thames.”
The RNLI, which is a charity that saves lives at sea and on the River Thames, urged people not swim in the river.