Environmental campaigner Lewis Gordon Pugh has become the first person to swim the length of the River Thames.
The 36-year-old lawyer, who wants to raise awareness about climate change, finished his 203-mile swim in Essex.
He started his bid at the source of the river in Gloucestershire on 17 July. "I am absolutely exhausted. It has been an incredible journey," he said.
"This challenge has proved far more difficult than I expected due to the drought and the heatwave."
The river is just a trickle at its source, so Mr Pugh ran the first 19 miles before taking the plunge.
The journey has taken him through Oxford, Reading and London, before heading out to the Essex coast.
On Thursday he stopped off to meet Tony Blair and discuss problems for the environment.
"I just hope that my swim has brought home the message that we have to do all we can to tackle climate change," Mr Pugh said.