Summiting Fenn made him the first person to complete the highpoints of each mountain range and subrange in Idaho — a list of 85 mountains that includes Mount Borah, Hyndman Peak and Castle Peak.

When Jeremy Powell stood atop Fenn Mountain in the Selway Crags, he was feeling pretty accomplished. Summiting the 8,021-foot mountain in remote North Idaho’s Nez Perce-Clearwater National ...