I don't remember any specific incidents of trauma, but I've been afraid of water for most of my life. Even in swim class I was scared and I was a teenager!

Well, there was that one incident with an inflatable raft that got tipped over in the deep part of a reservoir swim area. I felt very calm as I yanked my friend's hair to get to the surface. We recovered the raft before the lifeguard had to come rescue us. But I was scared the entire time I was on the raft, so...