You want to hear something crazy? I have a fear of water deeper than me. I'm about 5'7 and start to get nervous in water that's about 5'6.
But the crazy part is, I used to be a life guard. And I'm an excellent swimmer. I started taking lessons at a very young age, went through the highest level of lessons offered, I even TAUGHT swim lessons. I can tread water with no hands for 5 minutes in 7' (or, at least, I could about a decade ago).
But for some reason, deep water makes me nervous. Sometimes, I can get used to it (like in the 10' diving well where I used to work).
Today I was swimming laps at the local high school (residents can do lap swimming for free). I was in the shallow end (3' - 5'). They were setting up the pool for swim lessons, and about 20 minutes into my swim, they said I could move to the other side, since in about 10 minutes, the side I was on was going to be all swim lessons.
Well, the other side is 6.5' to 12' (maybe 12.5'). I said, oh, that's fine, I'll finish up by then.
Because I was to nervous to go the deep side.
This makes no sense! It's an indoor pool! There is no under toe! And I'm a very strong swimmer! I'm not even going to lie. My endurance isn't that great, but I'm a good swimmer. And I've simulated deep water unconscious with a possible spinal injury saves in 10' of water. (Again, about a decade ago ... but still.)
Oh well. Maybe one day I will get used to the deep end of this pool. Might take me a few weeks ... months ... year.