I imagine it as more of an attempt to engage with the bystanders, maybe to try and tell them that he can do better. "Ugh! I failed", he says, trying to smile in

I imagine it as more of an attempt to engage with the bystanders, maybe to try and tell them that he can do better. "Ugh! I failed", he says, trying to smile in the direction of the onlooking girls. A quick attempt at a chuckle to make light of the situation and he swims away. OTOH it does sound like the kid in question was a lot younger than 16, especially considering his reaction and the fact that he was at the pool with his mother.