A gang of teenagers attacked a man as he walked down the cliff path to Brighton Marina.
The gang of three boys and three girls approached the man at about 7.20pm on Sunday (19 December).
Sussex Police said that one of the boys punched him in the stomach and a second hit him in the face, breaking his nose, and was abusive to him.
The first boy is described as white, 5ft 6in tall, 15 to 16 years old, of average build with ginger hair short on the sides and longer on the top with a gelled fringe. He had acne.
He was wearing a dark top, possibly black, and light trousers.
The second boy is described as white, 5ft 7in to 5ft 8in tall, also 15 to 16 years old, of slim build with short dark hair.
He was wearing a dark blue padded jacket and dark blue jeans.
The victim was treated at the Royal Sussex County Hospital in Eastern Road, Brighton, for his broken nose and cuts and bruises to his face.
PC Adam Parris said: “We would like to hear from anyone who was in the area of the cliff path above the marina on Sunday evening and who saw the group involved in this clearly unprovoked attack.”
Witnesses are asked to call 0845 6070999.