Basically we were on a mini-cruise tour as part of a larger cruise tour.
The boat stopped, and we were swimming with nothing but the vast abyss below, and no land around. One of my Mum's friends thought I'd kicked him and decided, jokingly, to not only shove me under the water, but to swim down push me further, stand on my shoulders and kick off to get back to the surface, consequently pushing me down into said black void EVEN further.
Needless to say I spun around a lot and lost my sense of direction. Barely any light, nothing but water, and I hadn't had chance to take a breath before hand. My brain decided everything was moving and tried to make shapes where there were none, and then I started blacking out right as an intense pain ripped through my chest.
He was a 47 year old muscular man, I was a tiny 7 year old.
Luckily my Dad saw the whole thing and dragged me back up. Then when we were all on the boat, he punched this guy in the face and threw him overboard. He was sadly, mostly, unharmed.