Yellowstone National Park
Yellowstone National Park has one of the world's largest petrified forests, trees which were long ago buried by ash and soil and transformed from wood to mineral materials. This ash and other volcanic debris are believed to have come from the park area itself as the central part of Yellowstone is the massive caldera of a supervolcano. The park contains 290 waterfalls of at least , the highest being the Lower Falls of the Yellowstone River at .
Sulphide Creek
Meltwater from the Sulphide and Crystal glaciers skips several hundred feet down a series of Shuksan greenschist cliffs into Sulphide Lake, a small and nearly inaccessible tarn at on the southeast flank of Mount Shuksan. Sulphide Creek flows out of the lake and drops down a narrow, deeply incised rock chute forming Sulphide Creek Falls, one of the tallest waterfalls in North America with an estimated height of .
According to Canyoneering Northwest, the Sulphide Creek canyon has had "no record of descent or exploration".