Dakota Fred Hurt has been diagnosed with stage 4 brain cancer.
The news of the condition of the reality TV star, famed for his role on Gold Rush White Water, was confirmed in a statement by his entertainment company.
Thrill of the Hunt Entertainment LLC said he was currently looking at a range of possible treatment options.
He is said to be in good spirits despite the news.
Speaking to his company, Fred said: "I've lived a full 80 years of an interesting life. If I emerge from this dark diagnosis, I'll have another adventure to share with you folks."
Fred is best known for his role on the reality TV series and his thrill-seeking attitude.
He first featured on the show 10 years ago as cameras followed his pursuit of gold. Some of his most recent adventures so him tackle dangerous whitewater in Alaska.
He went on to co-own Thrill of the Hunt and is currently working on a number of potential film projects.
After news of his diagnosis, fans took to social media to send their messages of well wishes.
He posted the news to his official Facebook account and fans left their words in the comments section.
One user wrote: "I am so sad to read this! My husband always watches discovery & I saw an episode many years ago of Gold Rush, I adored you & continued to watch religiously because of you!
"My thoughts, prayers & love are with you on this journey. Enjoy what time you have & make any memories you can! My best friend just passed from Lung/Brain cancer 3 weeks ago."
Another added: "Hang in there Big Boot! You'll get through this, like everything else you've done in your amazing life. And if you don't, then it just wasn't meant to be.
"You've lived a GREAT life and been a huge inspiration to all your fans throughout the years and made your mark on the world. What a legacy to leave behind!"
And a third said: "Praying for you Fred, you've been such an inspiration to so many! And we appreciate you!!!"
Many others took the time to let him know he was in their thoughts and prayers.
