One way, Lassen Peak is 2.5 miles with 2,000 feet gain. The uphill is a steady, steep grade beginning at 8,500 feet and ending at the summit at 10, 462 feet. Mount Lassen is the heart of Lassen National Park and can be seen from most parts of the park. Like all the summit hikes in the park, this one offers wonderful vistas of the surrounding mountains and valleys.