The property, apparently owned by 34-year-old Benjamin Ludvig, was discovered by a member of the public on the coastal path at Cove, south of Aberdeen, at around 12.20pm on Monday.
That person had also seen a man wearing a red waterproof jacket in the same area the previous day.
Officers said they want to establish if that man was Mr Ludvig, whose connections to the area are not yet known.
Coastguard teams and the Aberdeen lifeboat have been carrying out searches of the coastline around Cove.
Inspector Mark Stephen, of Police Scotland, said: “Personal belongings apparently relating to Benjamin Ludvig, a 34-year-old German, were recovered near the cliff top on the coastal path near Cove.
“We are keen to establish if he was the male wearing the red waterproof jacket and that he is safe and well. At this time we don’t know what Mr Ludvig’s connections are to the area.
“I would ask that anyone who has any knowledge of the current whereabouts of Mr Ludvig, where he has been staying or any other information about him to get in touch with us on 101.
“Similarly if you were the male wearing the red waterproof jacket in the area on Sunday March 5 and are unconnected to Mr Ludvig we would like to hear from you too.”