My fear of water has little to do with water, per se. I grew up in Michigan, US. The Great Lakes State. Bitter cold winters, water was ice covered, it cracked and groaned, sometimes it was clear, sometimes it was just grey, but when the ice broke, it was the epitome of nature's violence. I've seen expensive, thick steel break walls be shredded like thin tin foil. I've seen people and their trucks, snowmobiles, and ice shanties go under. Some of my friends would jump onto those ice flows and ride them. They were fine, but every year you would hear of a kid to two going under. I will sometimes walk out onto the ice, but I am never comfortable, and I do it with deep respect.
I also understood very well what that deep water line meant. It meant if you went under it was going to be a long time before you hit bottom and no one is going to find you in the blackness. I like going out on the boat sometimes, but I am more comfortable being the one navigating, in control. If I am just sitting in a seat for the ride, I can't enjoy myself.
My sister loves white water rafting. She convinced us to go, and I was trying to be a good sport about it, but I have a good understanding of the physics behind moving water and how much shear power there is. I also understood what that meant if I went overboard. Needless to say, while everyone else was "whooping it up" in the boat all excited, I was just trying to maintain my composure. I did it. Checked that box. Never again.
You know how some people can get into the water and just seem to float? They are up on top of the water, totally enjoying the experience, laughing, playing, well, not me. I don't seem to float at all. I go straight to the bottom. So, I cannot relax in the water because I am struggling to keep my mouth above the water line, gasping for air. Put on a floatation device they said, still sank. Put on 2 floatation devices, still sank, and this was in Hawaii in salt water where everyone floats. I paid for an expensive snorkeling tour and had to watch my wife from the stupid boat while the life guards where dumbfounded why I couldn't keep my body above water enough to use a stupid snorkel.
So, just some examples of my fear of water.