Lava Canyon Falls is a 200-foot waterfall on the Muddy River in Lava Canyon on the southeast side of Mount St. Helens National Volcanic Monument in Washington. At about 2,440 feet elevation, it marks the largest sheer drop along a roughly 2-mile stretch where the river descends 1,400 feet through terrain dramatically altered by volcanic activity. The falls are closely linked to the 1980 eruption of Mount St. Helens, when a lahar and later floods scoured open a canyon that had been buried in dirt and mud for about 1,800 years and redirected the Muddy River into it. The waterfall remains a striking visible result of how quickly the eruption remade the landscape.