yeah, happened to me as well.
2 or 3 times, someone landed so close to me, if they had jumped just half a second earlier or if I'd been a tiny bit slower, they would have most likely broken my back or neck.
Not just kids, adults can be just as oblivious and careless, and if you tell them "btw I was there, you nearly hit me full on", they most likely talk back to you and tell you it's your fault for being there^^
(but germans do that all the time anyway, no matter the circumstances)

and if you're in open water instead, you always have to watch out for boats/surfers.
number one cause for diver deaths: run-in with boats.
I know no apneist who hasn't had a close call at least once :/