Brave Carolyn Smith of Skegness and her instructor and friend Phil May, of the Yellowbelly SUP School completed the journey from Lincoln to Boston in just over 10 hours.
However, it all nearly didn't happen after a worrying discovery at the start.
"We had a late start, then we found my board was broken," explained Carolyn. "I had given in and was ready to get back in the van and head home but Phil managed to fix my board and we set off hoping it would hold.
"Two hours later than planned, we touched the water."
Friends and family supported the intrepid duo along the way as they battled difficult conditions including a lot of weed in the River Witham.
With four miles to go, the wind and water were "evil". "My legs wouldn't adjust to the movement of the board so I had to push through in my knees," said Carolyn. "I started to feel sick from the motion. Halfway to Anton's I broke down - I couldn't go anymore.
"I managed to get a grip and crack on. I forced myself back up. We has planned to stop at Anton's Gowt but I couldn't - I needed to keep going otherwise I wouldn't make it .
"From Anton's Gowt, we were joined by a friend who has done our training plan for this. The last two miles went better than expected, I was so glad to see the Stump.
"At the 50km sign I just looked at Phil and grinned.
"We did it - we smashed it, with the paddling time of 10 hours and 8 minutes."
Afterwards, Carolyn thanked friends and family who had gone along to support her.
She was exhausted and said she just wanted her "bed and a cheese burger".
Next day a message on social media said: "Now for another hard part of the challenge, trying to survive the pain afterwards.
"Pain scale of a 8.5 this morning. I feel so sick from the pain.
"My legs won't hold my body weight anymore.
"My head feels like its going to explode.
"I've broken myself."
This year's challenge had been particularly hard as the face she most wanted to see amongst the crowd at the finish line was not there.
Carolyn suffers suffers from vascular ehlers danlos syndrome - and is at risk of her arteries and organs rupturing.
Her father, John, and supporter of the challenge also suffered the condition but sadly died at the age of 67 in May.
Since then, focusing on preparations for the challenge had not ben easy. She explained: "I had originally cancelled the challenge after the death of my dad. I'm grieving and trying to find a new normal after spending the last four years as his full-time carer but i want to do this for him now.
"It won't be easy and I will be a emotional wreck but I have to try.
"A Facebook friend messaged me the other day to see how I was and how I was feeling and I was very open about how I felt about Saturday.
"He make a great suggestion of taking a bit of dad with me, so I wrote a few things on my board in sharpie "This means nothing to anyone but me - childhood memories and more recent memories from these simple words."
After the challenge her final words were for her father: "Dad I did this for you and I really wish you could have been there.
"Every inch of my body hurt by the end but it was worth ever second of pain to help so many other people."
This is the third year of the challenge. In 2019 – along with her instructor and friend Phil May, of the Yellowbelly SUP School – the duo became the first to complete the 32 miles along the Witham from Lincolnshire to Boston on stand up paddle (sup) boards.
In 2020, they did the 32 miles in strong winds again . Carolyn also ruptured her knees again, but they completed it in 11 hours and 50 mins.
The duo set off from Lincoln on Saturday at 6am, travelling along the river via the Five Mile Bridge, Bardney Lock, Southrey, Kirkstead Bridge, Tattershall, Chapel Hill, Langrick and Anton's Gowt.
Their aim was to raise £2,000 for their chosen four charities - Royal National Lifeboat Institution (RNLI), The Lincolnshire And Nottinghamshire Air Ambulance Charitable Trust, Campaign Against Living Miserably (CALM), Annabelle's Challenge.
To make a donation, visit the Broken Hiker challenge 2021 here. at https://www.justgiving.com/team/brokenhikerchallenge3