The St. Anthony Sand Dunes are one of Idaho's great natural playgrounds, a vast sea of white quartz sand stretching some 20 miles long and 5 miles wide across the high desert northwest of St. Anthony in eastern Idaho. This 10,600-acre BLM Special Recreation Management Area holds dunes ranging from 50 to a towering 400 feet high, and it draws off-road riders, sandboarders, hikers and equestrians from across the region to a landscape that feels genuinely otherworldly against the backdrop of the Teton skyline.

Off-highway riding is the headline activity, and the dunes are built for it. The signature feature is Deadhorse Bowl, a famous OHV sand bowl a mile in circumference and 400 feet deep in the western part of the complex, where riders carve the steep faces from spring through fall. The BLM requires that off-road vehicles be registered in the owner's home state and fly a safety flag, a red or orange flag at least 6 by 12 inches, mounted 8 feet above the ground so machines are visible over the dune crests. Beyond the motors, the dunes are superb for sandboarding and sand sledding down the big faces, and for hiking and horseback riding in the quieter stretches.

Camping centers on Egin Lakes, about 8 miles west of St. Anthony, with 48 improved sites including some with electrical hookups, potable water, and an RV dump station; 26 sites are reservable on Recreation.gov and the rest are first come, first served. The area has a beach popular for swimming, though the lake does hold leeches, so staying near the shore's edge helps; in town, the St. Anthony Sandbar is a beloved local river swimming hole for a family picnic.

The dunes are exposed and can be punishing: summer sun bakes the open sand with no shade, wind kicks up quickly, and the soft, steep faces are genuinely strenuous to climb on foot. Riders should treat Deadhorse Bowl and the big faces with respect, and everyone needs far more water than the desert setting suggests. The sand also gets scorching underfoot at midday.

Spring and fall are the most comfortable seasons for riding and hiking, while summer draws the biggest weekend crowds and the swimming at Egin Lakes. Bring plenty of water, sun protection, eye protection against blowing sand, a properly flagged and registered machine if you're riding, and everything you need to be self-sufficient in open desert. For OHV thrills on 400-foot faces, a sandboard run, or just a walk across a genuine dune sea with the Tetons on the horizon, the St. Anthony Sand Dunes are a one-of-a-kind Idaho destination.