When I was a kid I was swimming in a children's pool in our backyard with my two younger brothers. One of my brothers was afraid to go under water. At one point

When I was a kid I was swimming in a children's pool in our backyard with my two younger brothers. One of my brothers was afraid to go under water. At one point, I turned around and noticed that he was underwater. It looked like he was making swimming motions as people normally do. I was surprised that he decided to do it, given his fear, and just watched him for maybe ten seconds. After some time passed I got concerned and pulled him up. Sure enough, he was drowning and I was just sitting there watching him. I learned that day how non-obvious drowning looks. I still feel bad about it to this day, even though he ended up being alright.