Diadem Peak is essentially the high point of a ridge leading down from the slightly higher Mount Woolley (3,405 m (11,171 ft)).

Upon reaching the summit, they discovered a crown (diadem) of snow about 30 m (98 ft) high covering the almost flat layer of rocks on top.

However, after a brief downpour which forced them to seek shelter among some rocks, they had just begun preparing the rope for ascending the icefield when a large collapse of ice from the summit made them switch their objective to Diadem Peak.

The party ascended the southeast ridge along loose shale and ice, eventually finding a small rock rib that took them to the summit on August 25.

[5] Jim Elzinga and Jeff Marshall made the first ascent up a mixed route on the North face of Diadem in July 1981.