Snoqualmie Falls

This beautiful waterfall is also a functioning power plant.  The Snoqualmie Falls Hydroelectric Plant is at Snoqualmie Falls, currently operated by Puget Sound Energy. It is made of two power houses, Plant 1 and Plant 2. Plant 1 was built in 1899 and operates at the base of the falls embedded in the rock 270 feet (82 m) below the surface. It was the world's first completely underground power plant. Plant 2 was built in 1910 and further expanded in 1957, and is located a short distance downstream of the falls. Approximately 1% of Puget Sound Energy sales comes from the plant. 

Source: Wikipedia