The Arkansas River begins its journey from its headwaters at Leadville, Colorado (11,000 ft.), Our half-day trip will run the Numbers section #1-7 rapids, starting just north of Buena Vista, CO. The Arkansas River – Numbers is truly home to world-class challenges of class IV rapids – running solid thrills from top to bottom. Consider any of the many other sections in the 145 miles of river rafting for the variety of whitewater levels to suit your expectations.