- The Mountain Loop Highway is home to many popular cascade hikes and climbs. There is no doubt that the scenic beauty of the Mountain Loop Highway Peaks far exceeds that of the I-90 corridor Peaks. There is more diversity in wildlife, foliage, and summit blocks are generally more rugged and exposed. The Mountain Loop Highway is a well kept secret among the locals of Washington State with the exception of Mount Pilchuck, trails are seldom crowded and tranquil isolation is the norm.