A man had his ear bitten off by another man in an "unprovoked attack" while swimming in a river with friends.
The 22-year-old man from Shirley Warren in Southampton, Hampshire, was swimming in the River Test near Redbridge when he was attacked from behind.
He was taken to Southampton General Hospital where he underwent surgery to have the ear re-attached.
Police said the identity of the attacker and the motive for the assault, on Tuesday, was a mystery.
They said the man ran off after biting the swimmer, but detectives were hopeful that somebody on nearby Redbridge Causeway, which was busy with afternoon commuter traffic at the time, saw him fleeing.