The most terrifying dive for me was one where I was caught in a typical FL summer storm.
Solo shore dive , with doubles no less. I was submerged steaming out to the third reef. Just past the second reef, I noticed how dark it got, seas picked up and pissing rain. Then the brilliant flashes. Lots of flashes. There was no way I was going to surface, from here or shore. I doubled back and stayed as deep as I could on by the second reef. I found a bored moray, so I kept myself busy chilling with with him.
Things calmed down after an hour or so and I made my way out.
From what I understand, when it strikes water the energy gets dispersed at the surface. How far down that travels, dunno.