Ha Thanh Tun, chairman of Khai Quang Ward in Vinh Yen Town where the bomb was found, said the bomb is 1.25 meters long, has a diameter of 0.4 meters and weighs around 340 kg.
It was found at the depth of 2.5 meters.
The authorities have evacuated all 430 families of 1,700 people that live in a radius of 500 meters to serve the work of unearthing and removing the bomb to a safe place for denotation.
While the Vietnam War ended more than 40 years ago, around 800,000 tons of unexploded ordnance remain scattered across the country, according to government data.