A childhood belief about swimming pools

I used to believe that in the deep end of one of our town's pools, there was a huge sea serpent that would kill you if you touched it. I never knew for sure, because it was the kind of pool that is designed to look like a lake, you know, with murky water and sand on the bottom. So one day, I decided to see if I could find it. I jumped off the dock in the middle of the deep end and swam straight down. Now, I was about 7 years old, and the pool was 18 feet deep, so once I got pretty far down, I was not thinking clearly. I had my hands stretched out, and my hand brushed something. I screamed while I was under the water, and swam as fast as I could (not very fast) to the surface. I was convinced that the monster was chasing me. So I burst to the surface and got on the dock, breathing heavily, as I'd almost lost conciousness by that point. I now know that I'd touched the bottom, but I was too scared to ever go in that pool again.