"No, not much." He could, obviously, either in his own shape or another. You didn't live on Asgard or spend any time fishing without learning how to swim. And when he'd been very young, it had been a favorite way to stay cool in the heat. But later.... "Blame my youth. My brother and his friends were... let's just say that when one's near-constant companions are three who hate you and the last thoroughly oblivious, one learns to avoid the water unless a boat is involved."