Stop by Susanville's Lassen Historical Museum. Near by Eagle Lake is California's second-largest natural lake, a popular place for fishing and boating. The Ash Creek Wildlife Area affords spectacular views of Lassen National Volcanic Park and Mount Shasta. Hike to the top of 10,457-foot Lassen Peak for a top-of-the-world view. Marvel at the bubbling geothermal mud pots and fumaroles in Lassen Park.