In a cavern, in a canyon..... Crossett Western #10 exits the 300 ft long, curved tunnel near Mouton Falls, and is seen here among the dense vegetation in the rock cut that marks the approach to the West Portal.
The tunnel you see here was constructed in 1901 by the Portland, Vancouver and Yakima Railroad, and is carved out of solid rock, requiring no support on the inside. Both portals of this tunnel are in narrow rock cuts, and both are covered with a dense tree canopy. If you try to find this tunnel on Google Earth, you'd either better have the coordinates, or know just where to look, because you'll never see the actual portals on the satellite imagery.