At Upper Mesa Falls, a thunderous curtain of water – as tall as a 10-story building – pours over remnants of an ancient volcanic super-eruption. A mile south, Lower Mesa Falls repeats the performance, the river continually chiseling away at the solidified ash and lava. The beautiful Upper and Lower Mesa Falls are the last prominent waterfalls on the Snake River unaffected by manmade influences. A scenic walking path leads to excellent viewpoints. The Mesa Falls Visitor Center is open daily in the summer and has limited hours on certain weekends during the winter. From the Visitor Center, an accessible trail and boardwalk provide spectacular views of Mesa Falls. Winter access is only available by snowmobile or skis.