"The 270 foot drop off a ledge of volcanic rock inspired Charles Baker's vision of the world's first fully underground hydropower plant."
Snoqualmie Falls, actually only 268 feet, is Washington State's most popular waterfall. The park offers free parking and a free viewing area.
There is an easy hiking trail, 1.2 miles round trip, to the bottom of the falls.
Tip: As you are driving towards the park, watch for overflow parking on the opposite side of the road. It kind of jumps up on you, but will easier to get into than the parking lot right in front of the park.