I just read this article and found it really terrifying. It points out that most people learn what drowning looks like from television and films, which does not realistically depict how people act when drowning. I had absolutely no idea and it is frightening to think that I could so easily have missed the signs.
Hopefully I am unusually ignorant on this topic, but if not please take a minute to read about the signs of drowning. Usually the person drowning makes no noise or hand movements.