There are more than 100,000 miles of river in the Gem State. Referred to as the "whitewater state," Idaho has more free-flowing whitewater than any other state in the U.S.—hence the rise in popularity of sports like whitewater rafting and kayaking.
"Whitewater kayaking has been our bread and butter for 30-something years," said Jo Cassin, co-owner of Idaho River Sports. "It grew a lot in the mid '80s [and] early '90s, but I would definitely say it's on the increase again."
Cassin took the deep dive into water sport rentals when she was in college. At the time, her boss had stopped doing rentals altogether, but when customers kept asking where else they might rent some gear, she and her business partner at IRS, Stan Kolb, picked up the slack.
"We do more of the rentals, but we do a lot of paddle boarding and flatwater kayaking classes," said Cassin. "And if people need whitewater lessons, we might send them to Cascade Raft and Kayak, Bear Valley or Payette River Company."
In Boise, residents don't have to travel very far to enjoy whitewater. The Boise River and the city's whitewater park provide access close to home. Since its debut in 2012, the Boise Whitewater Park near Esther Simplot Park has been open year-round, and features pneumatically operated wave shapers designed by Denver-based McLaughlin Whitewater Design Group.
"It's pneumatics and hydraulics in unison," said Boise Whitewater Park Wave Technician Paul Primus. "So the waves go over the splashboard; they're controlled by pneumatics. The hydraulic wave shaper's steel plates can lower or raise the height of the water. Lowering them will make the feature more retenant, so it will make a wave steeper, demonstrating a true hydraulic design jump park."
Wave-chasers of all stripes take advantage of those features. Surfers, kayakers, rafters and boogie board users fill the water park on any given mid-summer day (the majority are freestyle kayakers or short board surfers).
On certain days, operators shift the waves to accommodate each group of enthusiasts.
"The surfers like the green wave, a glassy-smooth wave; and the kayakers like a wave hole," said Primus. "Primarily, the whitewater that's on top of the wave hole is actually better for kayaking, and a green wave with minimal whitewater is great for surfing."
Primus said the Boise park's ability to adjust its features is what makes it so unique.
Whitewater kayaking and rafting aren't the only river sports growing in participants. Primus said he has seen a large increase in so-called shortboard surfing in the past three years, as well. Cassin added that Idaho River Sports' stand-up paddle boards are among its most popular rentals, but its rafts also get scooped up quickly.
"This year's been great," said Cassin. "All of our rental rafts are out right now, and we're expecting that to continue all the way through August. So, we're going to be adding more."