When it comes to the beauty and diversity of the surrounding landscape, not many rivers in the United States can compete with the Arkansas River. At 1,469 miles, it’s the sixth-longest river in the United States, flowing eastward from Colorado through Kansas and Oklahoma before finally emptying into the mighty Mississippi River in Arkansas. The first stretch is clearly the most spectacular section: From its source high up in the rugged Sawatch Range of Colorado’s Rocky Mountains, “The Arkansas” is a raging stream of crystal-clear snowmelt water, cascading downhill and thundering through awe-inspiring canyons, dropping more than 10,000 feet in elevation on the first 125 miles. It’s no surprise that this part of the river has become America’s favorite destination for...