Dozens of swimmers braved murky waters of a peat bog to take part in the 30th World Bog Snorkelling Championships.
The wacky competition saw around 130 competitors from across the world, some in fancy dress, descend on Waen Rhydd Bog on the outskirts of Llanwrtyd Wells, Powys, mid Wales.
They were cheered on by hundreds of spectators who were enjoying the August bank holiday ritual, despite the rain.
There are strict rules enforced by organisers as competitors swim two lengths of the 55-metre (180ft) trench as quickly as possible, keeping their faces in the dirty water and relying on a snorkle to breath.
They can only use doggy paddle as front crawl and breast stroke are banned by organisers, as are mono-fins and webbed gloves. Most choose to wear wetsuits but some hardy types do without.
The event regularly attracts participants from across the world, including France, Germany, Belgium, Portugal, Sweden, South Africa, Australia, New Zealand, USA and Japan.
The current world record holder is Kirsty Johnson, 33, from Surrey, who set the record last year at one minute and 22.56 seconds - beating the previous best by 0.15 seconds.
This year serial bog snorkeller Haydn Pitchforth, from Leeds, regained his world title in a time of one minute and 26 seconds - four seconds quicker than his nearest rival.
The first swimmer through this year was Joel Hicks, 36, from Leicestershire, who set a time of two minutes and seven seconds, raising funds for his foundation Always With A Smile.
He said: "It went well, apart from the first mouthful of water at the start.
"I work with a number of different charities and good causes putting a smile on the faces of as many people as possible."
Also taking part was Steve Meadows, 43, from Leicester, who tackled the course dressed as Elvis to raise money for the Rainbow children's hospice.
Describing the water, he said: "It's cold. I normally run the Great North Run and I wear a range of different costumes. I am fed up of dressing as Elvis, so I thought if I was going to ruin it, I might as well do it properly."
Gordon Green, 80, founded the competition 30 years ago when he ran The Neuadd Arms pub in the town as a way of encouraging tourism.
He said: "It has been a very good turn out with people from across the world taking part.
"We started organising the event to bring tourists into the town. Now people tell me that what we are doing has put Wales on the map."
Mr Green had some advice for anyone thinking of taking part in the future.
"You have to be a good swimmer, have the right sort of flippers and you have to be strong, as it's all about leg power," he said.
Run by a team of volunteers, the annual competition is part of a roster of eccentric events held throughout the year at Llanwrtyd Wells, the UK's smallest town.
It also hosts the Man Versus Horse Marathon and a bog snorkelling triathlon, which includes a seven-and-a-half mile run and a 19-mile bike ride, as well as two lengths of the infamous bog.
The same two trenches, home to fish and insects including the harmless but nasty-sounding water scorpions, are used every year.
Next year organisers are hosting the third bi-annual World Alternative Games, which sees events such as underwater rugby, wife carrying, husband dragging and office chair racing, held over two weeks.
"We have somebody who wants to put on extreme boules. They did it from the top of Pen y Fan and they lost the boules," Mr Green said.
"There's a quarry nearby and we're thinking of holding the boules in there and throwing them from the top into the bog at the bottom."