A crack team of bomb disposal experts were scrambled to a boat which dragged up a suspected World War Two mine in the Clyde.
The Royal Navy’s underwater munitions specialists from HM Naval Base Clyde, Faslane, raced to meet the vessel at Ettrick Bay, near the Isle of Bute.
Coastguard personnel safely brought the seven people on board back to shore.
Navy staff are expected to carry out a controlled detonation of the device tomorrow.
A Royal Navy spokesman said: “We can confirm that Royal Navy bomb disposal experts from HM Naval Base Clyde’s Northern Diving Group are on their way to Ettrick Bay, Isle of Bute, to meet a vessel with suspected ordnance on board.
“The team are expected to be at the scene around 5pm and will examine the item and most likely lower it to the seabed where a controlled explosion can be carried out at first light tomorrow.”
A spokesman for the Maritime and Coastguard Agency said: “HM Coastguard has been coordinating the response following a report that a vessel in the Firth of Clyde had found a possible ordnance.
“The report was received around 11.20am today on December 1 and the Explosive Ordnance Disposal Team were called in to assist.
"Police Scotland were also informed. Troon RNLI lifeboat was sent along with Rothesay Coastguard Rescue Team and seven people on board the vessel were safely brought back to shore.
“The disposal team is currently assessing how to deal with the ordnance.”