Northern California’s Lassen Volcanic National Park is a goldmine of volcanic features. At the center of the park is a plug-dome volcano known as Lassen Peak, one of only two volcanoes in the Lower 48 to have erupted since 1900. Every type of volcano can be be found within Lassen, as can many distinct hydrothermal features such as hot springs and mud pits. All can be seen by way of the park’s many trails, both for day hikers and backpackers. The park receives around 400,000 annual visitors, and it is crossed by the Pacific Crest Trail.