Police are becoming increasingly concerned for the welfare of Gary Michaels who is 70.
Gary left his home in Belfast and travelled to Coleraine in late August.
He was last seen posting a letter at Coleraine Post Office on New Row on Thursday 26 August at around 10.30am. He may still be in the north coast area.
He is believed to have a tent.
Gary is described as 6ft tall, of large build with an English or Isle of Man accent and short grey hair, and he may have a trolley case on wheels.
Anyone who may have any information about Gary’s whereabouts, or which could assist police with enquiries, is asked to contact 101 quoting reference number 960 of 31/8/21.