Rain failed to stop play when thousands of people took part in a charity challenge.
The Gung-Ho! event was held for the first time at Wynyard Hall, on the outskirts of Hartlepool, and more than 4,000 people took part.
Organisers said they were ‘gob-smacked’ by the success of the day and how much everyone threw themselves into it, despite the horrible weather conditions.
Thousands had already signed up in advance to do the muddy run and inflatable obstacle course, but many more turned up on the day both to take part and cheer on the contestants.
Alex Winters, one of the organisers, said he was impressed by the spirit of everyone taking part.
He said: “I was gob-smacked by the whole thing.
The amount that turned up on the day was absolutely staggering
“I think they were the worst conditions we have ever done the Gung-Ho in, it was freezing and raining and so muddy.
“But, the whole day, right from the start, was absolutely brilliant. People were running and sliding through the mud, they were having a fantastic time, the weather didn’t dampen their spirits one little bit.
“I think people just had a great time.
“The amount that turned up to run on the day was absolutely staggering. I think I would have looked out of the window, seen the weather and gone back to bed.”
Alex said this was the first time the organisers had used Wynyard Hall to host they event and he said it couldn’t have been better and he hopes they can come back again next year.
Gung-Ho!, which is a fun inflatable 5k run, has seen 100,000 people taking part since is started in 20015.
Many people just do it for fun, but for lots of people it is a way of raising money for charities close to their hearts.
Gung-Ho! has proved so successful, organisers are hoping 2018 will be the biggest year yet.
As well as raising money for its partner organisation, Children In Need, the group also partners with a local charity wherever it does and at the weekend this was the South Tees Hospital Charity.
Alex said: “Everyone from the charity was fantastic, running around all over helping people, and about 60 of them took part to raise funds.”
The goal of Gung-Ho! is to now bring the event to even more cities and more people to give them the chance to experience something new.
A number of Hartlepool people took part in the event, including nine friends and family members who signed up to raise money for Motor Neurone Disease Association, in memory of Brian Hamilton, 75, who lost his life to the disease.
There are lots of Gung-Ho! events going on across the country over the year and for more information about them visit the website begung-ho.co.uk.