An extensive search of the Nitmiluk National Park walking trails has so far failed to locate missing Melbourne tourist Daymon Ness.
It is now five days since he went missing.
Mr Ness, aged 30, failed to return from a walk at Nitmiluk on Tuesday.
His car is still in the public carpark at the gorge.
"Together with Parks and Wildlife staff and local helicopter operators, we have searched the gorge area, including the Jatbula and other trails, campground and the river, without locating Mr Ness," Superintendent Daniel Shean said.
"We will continue searching and we are very keen to speak with anyone who may have seen Mr Ness in the Katherine area on Monday or Tuesday."
Mr Ness came to the Top End for a holiday and quarantined for the required 14 days.
He traveled around the Darwin area and hired a car on Monday and drove alone to Katherine where he stayed the night.
On the Tuesday, he drove to the world famous gorge and arrived there about 1pm on Tuesday.
Despite temperatures hovering about 40 degrees for much of the week, Mr Ness texted a friend to say he was going for a walk.
He is described as a Caucasian male, thin build, 185-190cm tall, dark brown hair, hazel eyes and was last seen wearing a black top, green/grey pants and red shoes.
Police are appealing to anyone who may have seen Mr Ness or knows of his whereabouts to contact them on 131 444 or CrimeStoppers on 1800 333 000 and quote reference 9458035.
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