Mount Saint Helens National Volcanic Monument

Windy Ridge is a ridge and eponymous Forest Highway in the Mount St. Helens National Volcanic Monument. The ridge goes between Windy Pass and Independence Pass, 1 mile (1.6 km) east of Spirit Lake. Several road guides list Windy Ridge Road (NF-99) as one of the best roads in Washington State due to its good pavement, good views, and winding "sweeper" curves enjoyable to many drivers and motorcycle riders. At the end of the road at 4,200 feet (1,300 m) elevation, at 46°15′00″N 122°08′14″W above Spirit Lake, there is a viewpoint into the St. Helens crater.

On March 27, 1980, a series of volcanic explosions and pyroclastic flows began at Mount St. Helens in Skamania County, Washington, United States. A series of phreatic blasts occurred from the summit and escalated until a major explosive eruption took place on May 18, 1980, at 8:32 am. The eruption, which had a volcanic explosivity index of 5, was the first to occur in the contiguous United States since the much smaller 1915 eruption of Lassen Peak in California. It has often been considered the most disastrous volcanic eruption in U.S. history.

The 2004–2008 volcanic activity of Mount St. Helens in Washington, United States has been documented as a continuous eruption in the form of gradual extrusion of magma. Starting in October 2004 and ceasing in January 2008, a new lava dome was built up. The new dome did not rise above the rim of the crater created by the 1980 eruption of Mount St. Helens.

The Yn tephra is a geologically recent tephra deposit that covers portions of the U.S. state of Washington and the Canadian provinces of British Columbia and Alberta. It was created by the largest known volcanic eruption from Mount St. Helens, having taken place in possibly 1860 BCE as part of the Smith Creek eruptive period. The tephra consists of pumiceous dacite.

Goat Marsh Research Natural Area is a 1,195 acres (484 hectares) research natural area located southwest of Mount St. Helens and within Mount St. Helens National Volcanic Monument. The area has been identified as a region of scientific importance and preserved for ecological research due to its recent volcanic history as well as for its large tracts of mature and undisturbed noble fir forest.