A World War Two mine found in the Firth of Clyde contained about 350kg (771 lbs) of explosives.
The BBC reported that a “pristine” German-laid mine was discovered by the crew of a Marine Scotland research boat near Wemyss Bay on Wednesday.
Seven crew members were evacuated by lifeboat before their vessel was sailed to Ettrick Bay on the Isle of Bute.
Bomb disposal experts then carried out a controlled explosion of the mine.
Lieutenant Commander Mark Shaw, Commanding Officer of of the Royal Navy’s Northern Diving Group, said the submarine-laid mine was in “remarkable” condition considering it had been in the water for 80 years.”
“Carrying-out a controlled explosion is the only safe way of dealing with them and neutralising the hazard.”
He said that anyone who comes across a suspected piece of ordnance should not interfere with it and immediately contact the emergency services.