Comedian David Walliams will be at London's Aquatics Centre today as he helps launch this year's SwimBritain campaign to get the British public swimming.
The initiative is backed by British swimming stars including Rebecca Adlington, Ellie Simmonds and Michael Jamieson.
The campaign hopes to get half a million people across the country interested in swimming and in keeping fit.
The Great London Swim will be moved to Millwall Dock for the event on August 31, after tests at the Royal Victoria Dock found the water to be unsafe for immersion sports.
Alex Jackson event director of the Great Swim Series said: “The change in water quality has been unprecedented.
“The safety and comfort of our swimmers is our number one priority, and to ensure we can still provide them with a great open water experience in London, we are moving the event to the nearby Millwall Dock, which has always been on standby as a suitable alternative venue.”
The event will now take place at Docklands Sailing & Watersports Centre at Millwall Dock.
A teenage boy and a man who drowned while swimming at a beauty spot have been named by police.
Umar Balogun, 16, from the Waltham Forest area of east London and Ryan Pettengell, 41, from King's Lynn, Norfolk, died at Bawsey Pits, a disused quarry near King's Lynn, on Tuesday.
Their bodies were recovered from separate lakes following a major search and rescue operation by emergency services, after both had separately been reported getting into difficulties in the water.
Post-mortem examinations carried out yesterday confirmed the cause of death for both as drowning.
Inquiries continue by police, in conjunction with the Health and Safety Executive and King's Lynn and West Norfolk Borough Council, to establish the circumstances surrounding the deaths.
London Mayor Boris Johnson posed for photos as a new scheme was launched, which has brought mobile swimming pools to local communities at 18 London venues.
Speaking at Maria Fidelis School in Camden, north London, Mr Johnson said: "The Make a Splash campaign has seen kids of all ages taking the plunge and trying a sport that offers one of the best forms of exercise known to man.
"As we continue to build on the momentum of last year's Olympic and Paralympic Games, I'm delighted to confirm that the mobile pools will be making yet another tour of duty across the capital so that more people can get the opportunity to take a dip."
Anyone who is interested having a mobile pool to come to your school or community facility can go online here.
More than 19,000 youngsters have been taught to swim as part of a scheme which has brought mobile swimming pools to local communities, it was announced today.
The impact has been recorded in the three years the Make a Splash scheme has been running across 18 London venues, according to mayor Boris Johnson.
Another eight venues have now been earmarked as a base for the scheme which is run by Total Swimming and the Amateur Swimming Association (ASA).
Tooting Bec Lido in South London Swimming Club hosts the 5th UK Cold Water Swimming Championships today.
With water temperatures as low as 1°C, jumping in for the 30 yard races is a challenge in itself.
Anthony Stephens, who is originally from Reading, qualified for the final of the S5 200m freestyle this morning after finishing second in his heat.
But there was disappointment for James Hollis from Essex, who missed out on the S10 100m butterfly final. He came fourth.
His sister Emma pulled out of her heat in the SB7 110m breaststroke.
Rebecca Adlington joined the silver medallist Michael Jamieson at a pool in Ealing today, the first stop on their tour of British pools, to inspire youngsters to take up swimming.
Emma Walden has the story.
Olympic silver medallist Michael Jamieson was also at the British Swimming Heroes event at the Gurnell leisure centre in Ealing.
He told Emma Walden that it was an exciting time to be involved in the sport.