SR 821 is designated as the Yakima River Canyon Scenic Byway by the state government, recognizing its natural beauty and recreational opportunities. The byway is visited by 1.1 million drivers annually, of which a third visit recreational areas and campgrounds along the route. The canyon was formed approximately 10 million years ago through the erosion of rocks formed by basalt lava flows. The byway passes through shrub-steppe habitats that are home to trout, bighorn sheep, mule deer, and a variety of visiting or permanent bird species. An interpretive center for the byway was planned to be constructed at Helen McCabe State Park at the north entrance of the byway, using funding from the county government and the Federal Highway Administration, but was cancelled in 2015.