The Peterhead and Fraserburgh lifeboats were launched on Wednesday to a report of a missing person from a ferry travelling from Aberdeen to Lerwick.
The request to launch by the UK Coastguard was received at 11.37pm on June 27.
The Peterhead lifeboat, and over 30 other vessels, carried out a thorough search of the area that the casualty was thought to be in. Fraserburgh lifeboat and a rescue coastguard helicopter also searched the area.
The search went on for around seven hours but no casualty was found.
The search was resumed with Peterhead, Fraserburgh and Aberdeen lifeboats the following morning from 10am until 5pm with no success.