The device is thought to date back to Spain's 1936-39 Civil War and was discovered 25 metres from the shore, by an off-duty police diver.
ADVERTISEMENTTourists relaxing on one of Barcelona's most popular beaches were caught by surprise on Sunday after an explosive device was discovered off Sant Sebastià beach.
The device appeared to be old, possibly dating back some 80 years to the Spanish Civil War of 1936-39, the Civil Guard said. Located 25 metres from the shore, at a depth of 3 metres, it was found by an off-duty police diver who happened to be swimming in the area.
Police evacuated the area and established a security perimeter of 250 metres around the device, but despite advice to stay away, hundreds of locals and tourists continued to sunbathe on nearby beaches.
One tourist from Florida in the US named Nadia said: "I just found out about the bomb. That was pretty shocking. We were thinking like flesh-eating bacteria or like maybe someone who drowned, but I was not expecting a bomb from the Spanish Civil War. That was pretty surprising, pretty exciting for like the third day in Barcelona."
Navy specialists will arrive on Monday to deactivate the device, the Civil Guard said, adding that the closure would remain in place until the area is made safe.