If most of us had three weeks holiday off work, we would want to go somewhere warm and have a rest, but this is not the plan for Kevin Brady who is swimming the entire length of the River Severn, all 220 miles of it, for charity. It's the equivalent of ten English Channel swims.
If the 32-year-old, who's from Gloucester, completes the challenge, he'll make history by being the first person to finish such an adventure.
He'll have to battle hypothermic water, sharp debris, treacherous undercurrents, parasites, pollution and large boat traffic as complete more than 10 miles a day.
All money raised will go to Superhero Foundation, a charity Kevin co-founded with cousin and fellow fundraising adventurer Jamie McDonald. The charity assists families that need funds to access otherwise inaccessible treatments for mental or physical illness.
To donate visit: uk.virginmoneygiving.com/fund/kevssevernswim
You can watch Katie Rowlett's report on Kevin Brady's challenge here: