UK tsunami fears over shipwreck as wave could 'break every window' in seaside towns

Off the Kent coast, a sunken vessel is closely monitored by authorities due to its risk of exploding and causing a tsunami within the UK.

The SS Richard Montgomery, an American Liberty-class cargo ship, left Philadelphia in 1944 bound for Cherbourg, carrying more than 6,100 tons of munitions to support Allied forces following the Normandy invasion.

As it neared the Thames Estuary, strong gales forced the vessel to drag her anchor across the middle sandbank near Sheerness, where it ran aground.

A Rochester-based stevedore company was brought in to salvage the ship's cargo, beginning work on August 23, 1944, using the ship's own handling equipment. But within 24 hours, the hull had cracked, flooding several holds in the bow section and making a full recovery impossible.

The salvage team continued efforts for a month before abandoning the ship on September 25. Eventually, the vessel broke into two separate parts roughly amidships, leaving a significant portion of its deadly cargo behind.

Over the decades, repeated salvage proposals have failed, and the Montgomery has remained on the seabed ever since. Today, her three masts still rise eerily above the surface, ringed with marker buoys to deter anyone from venturing too close.

Because of the large quantity of unexploded ordnance, the site is under constant observation by the Maritime and Coastguard Agency, and is prominently marked on Admiralty charts.

In 1973, the wreck was designated as dangerous under the Protection of Wrecks Act, becoming the first site protected under that legislation. There is a permanent exclusion zone around the Montgomery, which is actively monitored with CCTV and radar systems.

In May 2025, the Secretary of State for Transport introduced additional restrictions, banning aircraft from flying below 13,100 feet within a radius of one nautical mile from the wreck. Professor David Alexander of The Royal Military College of Science concluded that a 3,000 metre-high column of water, debris, sand... and a five metre-high tsunami would be the "worst case scenario".

A Department for Transport spokesperson confirmed the wreck was still regarded as stable but said monitoring would continue.

One of the main reasons the explosives have never been removed stems from a disastrous attempt in July 1967 to neutralise the Kielce, a Polish cargo vessel that had sunk off Folkestone in 1946.

During the preliminary stages of that salvage, the Kielce exploded with a force equivalent to a 4.5-magnitude earthquake, gouging a six-metre-deep crater in the seabed and sending shockwaves that caused panic in Folkestone, even though no injuries were reported.

The Kielce had sunk in deeper water, farther from shore than the Montgomery, and was carrying only a fraction of the munitions now lying off Sheerness.

Previous studies have warned of potentially devastating consequences should the Montgomery's cargo ever detonate.

A 1970 BBC report concluded that an explosion could launch a column of water and debris up to 3,000 metres into the air, creating a wave five metres high and powerful enough to break almost every window in Sheerness, damaging nearby buildings and flooding low-lying coastal areas.

More recent reports, including one by BBC Kent in 2012, suggested the resulting wave might be closer to one metre high - significantly lower, but still capable of inundating coastal communities.

For now, the SS Richard Montgomery remains one of Britain's most dangerous and closely watched wrecks, a ghost of the Second World War resting under 15 metres of murky water - its cargo still threatening, after over 80 years, to unleash catastrophic consequences if ever disturbed.