David Allen, 21, disappeared from Denali National Park on July 25, 1973, after setting out for a day hike from Eielson Bluffs toward the Red Mountain area. He was carrying a neutral-colored day pack, an ice axe, a 35mm Pentax camera, and binoculars in a brown case. Witnesses described his clothing as an off-white wool sweater, a tan or dark green chamois shirt, and Levis he may have later changed into shorts; his footwear included red tennis shoes and Vasque hiking boots with Vibram soles, and he wore amber-colored glasses.

David is described as a white male with blond or strawberry blond hair, brown eyes, and a scar on the back of his head where hair did not grow. Multiple search and rescue operations scoured the route between Eielson Bluffs and Red Mountain, but the extensive searches failed to locate him or his belongings. There are no known witnesses to what happened after he left for the hike.

Anyone who was in the Eielson Bluffs or Red Mountain area on July 25, 1973, or who may have seen David or his belongings that day is asked to come forward with information.