Mount Dagelet is a 9,800+ ft (2,990+ m) glaciated mountain summit located in the Fairweather Range of the Saint Elias Mountains, in southeast Alaska, United States. The peak is situated in Glacier Bay National Park, 4.6 mi (7 km) south of Mount Crillon, and 4 mi (6 km) northwest of Mount La Perouse, which is the nearest highest peak. Topographic relief is significant as the mountain rises up from tidewater in less than nine miles. The mountain was named in 1874 by William Healey Dall of the U.S. Geological Survey, for Joseph Lepaute Dagelet (1751-1788), a French astronomer and mathematician who accompanied Lapérouse when he explored this coastal area in 1786. The first ascent of the peak was made July 29, 1933, by W. S. Child, C. S. Houston, and H. A. Carter.