A Portuguese fisherman in Nazare, around 120 km north of Portuguese capital Lisbon, found an unexploded bomb, believed to be from World War II.
The bomb, equivalent to 600 kg of TNT, was detonated by Portuguese navy divers safely at sea on Monday afternoon, Xinhua news agency reported.
The detonation was carried out 25 meters under water and around 1,000 meters away from the coast.
An area with 300 perimeters was sealed off to ensure the safety of the detonation.