The incident happened on the afternoon of 10 August 2020 in Nidd Gorge, in a wooded area near the river while a number of people, including children, were in the area.
The man is described as white, aged between 50 and 60 and was naked apart from dark coloured hiking boots, a baseball cap and a black watch. He had noticeable tan lines around his legs and carried clothing in his left hand.
Officers are asking members of the public to get in touch if they can help identify the man in the images as they believe he will have information that will help the investigation.
The incident is one of a number of similar incidents reported over the past year and officers are looking into whether or not the incidents are connected.
If you wish to remain anonymous, you can pass information to Crimestoppers on 0800 555 111.
Please quote reference number 12200150877 when passing on information.