A dripping wet fully-clothed man was seen walking up Peasholm Gap following a full-scale search on Saturday night.
Two lifeboats, two helicopters and two coastguard teams combed the area near Scalby Mills for over an hour, to no avail.
An off-duty lifeboat crew member was one of two people who reported someone in the water, possibly in distress.
“The area was quickly saturated with two airborne units, both lifeboats and two teams of coastguards but we couldn’t see anyone,” said inshore lifeboat helm Pete Billingsley.
On a calm sea and an ebbing tide, and with good visibility, the inshore lifeboat was launched at 8.30pm, rapidly followed by the all-weather lifeboat, coxswained by Lee Marton.
The lifeboats and coastguards combed the shoreline and sea in the North Bay, focusing on Mascus rocks but then widening the search.
The coastguard and police helicopters scanned the area with powerful beams.
Coastguard station officer Mark Jenkinson said: “The search continued for some time without finding anything.
“An eye-witness later said they saw a fully-clothed man, dripping wet, walking up Peasholm Gap. Having found nothing else it was presumed that this was the person in question and the search was called off.”
Lifeboat operations manager John Senior added: “Although nothing was found, seen from where I was standing, on the beach, this operation appeared to be a good example of inter-agency cooperation.”
If you see anyone injured or in distress on the coast, dial 999 and ask for the coastguard.