The Peterhead lifeboat was called out on Saturday afternoon after a reported sighting of a man entering the sea.
The man was reported to have entered the water next to Peterhead Golf Club and the UK Coastguard requested the lifeboat to launch at around 1.34pm.
After a search of the River Ugie mouth, the lifeboat crew did not see any casualties and stood down at 2.17pm.
After returning to the lifeboat station it was discovered that the man was a regular swimmer and he had returned home prior to the arrival of the lifeboat at the scene.
The call will be designated as a false alarm with good intent.