Poland: Massive World War 2 bomb detonates underwater during navy operation

POLAND (AFP) - An enormous World War II bomb has detonated underwater after Polish navy divers attempted to make the device safe.

None of the demolition experts were injured in the blast.

The explosive device — nicknamed "Tallboy" and capable of causing a small earthquake —was discovered in September last year at the bottom of a shipping channel in Swinoujscie, on the Baltic coast.

A relic of World War II, the bomb was dropped by the British Royal Air Force in an attack on a Nazi warship in 1945 and was only found during dredging of the access road to the port of Szczecin, in north-west Poland.

The delicate operation to defuse the bomb was described as a "world-first" by Grzegorz Lewandowski, spokesman for the 8th Polish Coast Defence Fleet.

"No one has ever neutralised such a well-preserved Tallboy lying at the bottom of the water."

Around 750 residents were evacuated from their homes on Monday during the high-risk operation.

The intention had been to try and neutralise the bomb by burning out its explosives, but in the end, it was detonated without damage.

Lewandowski assured that the explosion was "without risk for those directly involved in the operation", and the bomb "can be considered as neutralised".

A spokesman for the Świnoujście town hall told AFP that there was "no damage" to people's health, buildings, or the town's infrastructure.

A 2.5-kilometre security zone had been established in the area and all traffic in the port has been suspended during the operation, the local mayor confirmed in a statement on Monday.

Some residents told AFP they have refused to leave, saying the "main danger" was the risk of catching COVID-19 in a sports hall where residents are being given shelter.

The "Tallboy" bomb was 6 metres long and contained 2.4 tonnes of explosives - equivalent to around 3.6 tonnes of TNT.

It wasn't the first time that Swinoujscie's clearance divers had had to deal with lower-powered explosives found in the vicinity of the channel, the site of massive bombing during the Second World War.

Swinoujscie was regarded as one of the most important bases of the German navy on the Baltic during both world wars.

In April 1945, Lancaster bombers from the 617th "Dambusters" Squadron dropped twelve "Tallboys" on Germany's Lutzow cruiser in the region.

The ship's cannons were being used to hold back the advance of the Soviet Army and the Lutzow was eventually seized for target practice after the war.

Experts do not know why the "Tallboy" failed to explode in 1945.