They will do a little fishing, have a little friendly competition and do a lot of good.
The inaugural Two-Fly Derby will pit 20 fly anglers against each other on April 27 at a private reservoir in the Owyhees.
The rules are simple: Each person draws two random flies they must use to fish with and the biggest fish wins bragging rights.
The entry fee is $300 per angler and while that may seem steep to some people, the event quickly sold out.
That's partly because the derby is about more than fishing; it's to help cancer patients.
The proceeds will help fund Reel Recovery, which provides men in cancer treatment and cancer survivors an opportunity to go fly fishing and share their experiences.
"We provide them an expense paid retreat experience, which combines fly fishing with group therapy," said Two-Fly organizer Dick Wilson, a Boise neurologist.
Wilson helped start the retreats in Idaho in 2009, and he has been involved ever since.
He said each retreat serves about 14 men, and he works with hospitals and cancer centers in the state to find participants.
"I focus on getting people who are currently getting treatment," he said.
The weekend retreats typically cost about $10,000, and although Reel Recovery is a national organization, most of the cost of each one is raised in Idaho and used in Idaho, Wilson said.
The retreats are typically held at a resort so the men are comfortable and well fed.
The retreat includes a professional therapist and a crew of volunteer "fishing buddies," most of whom also are cancer survivors or people familiar with what the participants are going through.
The fishing buddies pay their own way on the retreat.
Each retreat serves seemingly contradictory purposes. It allows men to spend a couple days fly fishing on a beautiful trout stream and temporarily forget about dealing with cancer.
But it also brings the men together to learn how others are coping with the disease and draw inspiration from those who've survived it.
This year's retreat will be held in August at the Wildhorse Ranch in Copper Basin, north of Ketchum.
The Two-Fly event will help pay for this year's retreat and Wilson plans to make the derby an annual fundraising event for Idaho's Reel Recovery retreats.
And while the derby's focus is on raising money for Reel Recovery, the perks are pretty attractive.
Junayo Lake is a private fishing reservoir that is managed by Anglers fly shop in Boise. The lake is well-stocked with trophy-sized rainbow trout that typically run in the 16- to 22-inch range and some grow close to 30 inches.
The fish are stocked as fingerlings and allowed to grow naturally, and they're heavy, vigorous, hard-fighting fish.
Anglers get to fish all day at the reservoir and a Dutch-oven lunch will be cooked by outfitter Jerry Hughes of Hughes River Adventures.
Bucks Bags in Boise is also donating hats for the event.
"People are there for a good time, friendly competition, camaraderie and the money they spend will support men in need," Wilson said.
For details on the event, call Anglers at 323-6768.
For more information on Reel Recovery go to reelrecovery.org.
Roger Phillips: 377-6215, Twitter: @rogeroutdoors