A red flare fired into the sky over the Penryn River sparked a fruitless search by the Falmouth lifeboat yesterday.
Falmouth Coastguard requested that the all weather lifeboat be launched, alongside the station's boarding boat just after 3.30pm.
The Falmouth Coastguard Cliff Rescue Team was also tasked to assist in the search.
The Falmouth All Weather Lifeboat and boarding boat left the pontoon berth at 3.41pm and headed up the harbour commencing their search of the Penryn River at 3.48.
The whole river was searched from Flushing and Greenbank up as far as Penryn Quay and Islington Wharf using the all weather lifeboat, its small inflatable Y Boat and the boarding boat but nothing was found.
At 16:50 all units were released to return to station.
A Falmouth RNLI spokesman said: "The source of the flare has not been confirmed but it may well have been fired from the shore maliciously. At the time of the incident the Inshore Lifeboat was unavailable as it was undergoing maintenance."
Crew: Luke Wills (Coxswain), John Blakeston, Andy Jenkin, Claire Angove, Neil Capper, Derren Plaister
Location: Penryn River
Weather: NE 1, Calm Sea and No Swell, Good Visibility, Partly Cloudy