Ethan's activity of choice since he could walk, and grab a rock in his chubby little hands, was to throw rocks. We gave him appropriate places to do it, his favorite being into a little stream behind my mother's house. He spent lots of time with my mom just throwing rocks as a little kid.
All my boys enjoy throwing rocks (is that like saying they all like candy?) I have gone places with the intention of allowing them to throw rocks into a stream or a pond only to have other mom's telling their kids repeatedly to 'put the rocks down'! My kids would shoot me a glance to see what I expected of them - go right ahead I would tell them.
I taught them very early on to throw rocks when there was nothing between them and the water - like other people! I also showed them when and where we would throw rocks and where we would not. I feel like because they had chances to do it when they wanted - they were willing to abstain when I asked them to.
Let them throw rocks! It is fun and feels really good - go ahead, try it.
Dangerous? A little bit. The risks are mild if the parameters and settings are right.
What we remember from childhood we remember forever - permanent ghosts, stamped, inked, imprinted, eternally seen. ~Cynthia Ozick