What a Tragedy!
Back in the 1970's, my brother saw a German lady go over Vernal Falls. Those pools at the top look really inviting on a hot day. The water is calm, and the pool goes back at least 100 feet upstream as I recall. Last time I was up there, my kids kept begging me to let them go in the pool but there's no way that was going to happen.
If you look at this video you'll see that the shallow pools don't look very threatening, but obviously that’s not true.
http://www.youtube.com/watch?v=OgVKSE81KjU
Be safe out there!