(Update June, 2019: Floods have washed out the trail. The hike is short but is now a bit rough. You've got to climb over bounders and hop from rock to rock. It is a fun hike worth the trouble.)
This is a small, scenic waterfall just off Hwy 9 in Zion National Park. Between Canyon Junction and the switchbacks, Hwy 9 crosses a bridge over Pine Creek. Park by the bridge and just follow the trail upstream. It is an easy, short hike suitable for families with young kids.
The pool under the waterfall is shallow - good for wading but not swimming. However, downstream there are deep pools where swimming is possible.
Location: 37.216478°, -112.963814°