The Scream: My interpretation

I think the reason why he is screaming is because he just saw something bad happen. He saw one of his friends just slip and fall into the water and didn’t know how to swim and drowned. He didn’t know how to swim either so he just screamed as loud as he could to see if anybody would here him. But nobody heard him scream, so he just stood there screaming his lungs out until somebody did here him.