David Walliams is in the final day of his epic swim along the length of the River Thames for Sport Relief.
The comedian and actor has raised nearly £1 million for the charity, nearly four times more than his target.
On Sunday, thousands of supporters cheered him as he reached Teddington in south west London, after a 21-mile swim, his longest day yet.
He'll continue through the capital and aims to reach Big Ben at about 6pm on Monday evening.
It's been a really tough journey for David, who's battled the cold water temperatures and fought off a serious tummy bug to carry on with the swim.
But it's the final leg that's the most dangerous, as the tide and currents become stronger in London.
Over the weekend, he even managed to find the energy to rescue a dog that was stuck in the water and couldn't get out!
David's says he's been overwhelmed by the support he's been getting along the way: "I never expected this to catch the public's imagination like it has - there seems to have been a real carnival atmosphere around it which is lovely."