Slate Peak is a seven thousand four hundred forty-foot mountain in Washington’s North Cascades on the boundary of the Pasayten Wilderness and the line between Okanogan and Whatcom counties. Known more for access than technical climbing, it is reached by a narrow dirt road widely described as the highest in Washington, with the last stretch traveled on foot. Trails also cross its slopes, and its summit has offered broad mountain views. Slate Peak was also the site of Washington’s highest fire lookout, first built in 1924, later replaced, added to the National Historic Lookout Register in 2000, and found collapsed in the winter of 2025–2026.