Gwent Police are appealing for information to find Ben Aston from Hereford, who has been reported as missing.
Ben was last seen in Monk Street, Abergavenny at around 11.50am on Wednesday, August 28.
He is described as around 5 ft 10 inches tall, of stocky build with short brown curly hair and has a gap between his two front teeth.
Ben was last seen wearing all black – black leggings/bottoms, black t-shirt and carrying a black rucksack. He is believed to have travelled from Cornwall and has his surfboard with him.
He has known links to Shropshire and is thought to have headed towards Abergavenny railway station on Wednesday.
Anyone with information on his whereabouts is asked to call officers on 101 or send a direct message on social media, quoting log reference 2400288241.
Ben is also urged to get in touch with police.