According to experts a tsunami in the Bristol Channel could have caused the deaths of as many as 2,000 people in one of Britain’s greatest natural disasters.

For centuries, it has been thought that the great flood of January 1607 was caused by high tides and severe storms. It is estimated that 200 square miles of land in south Wales and south west England were covered by water. Eyewitness accounts of the disaster, published in six different pamphlets of the time, told of “huge and mighty hills of water” advancing at a speed “faster than a greyhound can run” and only receding 10 days later. Professor Simon Haslett, from Bath Spa University College, said: “There is an overall theme running through the pamphlets of a destructive event, very violent, disastrous, on a scale that is unprecedented.” Australian geologist Ted Bryant, from the University of Wollongong, agreed: “The waves are described as mountainous – that’s a description of a tsunami.” Read all (BBC)
Bristol Channel floods, 1607 (Wikipedia)
On 30 January 1607 the Bristol Channel floods resulted in the drowning of an estimated 2,000 or more people, with houses and villages swept away, an estimated 200 square miles (518 km2) of farmland inundated and livestock destroyed, wrecking the local economy along the coasts of the Bristol Channel. The devastation was particularly bad on the Welsh side from Laugharne in Carmarthenshire to above Chepstow on the English border. Cardiff was the most badly affected town. The coasts of Devon and the Somerset Levels as far inland as Glastonbury Tor, 14 miles (23 km) from the coast, were also affected.
There remain plaques up to 8 feet (2 m) above sea level to show how high the waters rose on the sides of the surviving churches. It was commemorated in a contemporary pamphlet God’s warning to the people of England by the great overflowing of the waters or floods.
“Gods Warning to his people of England.”. The British Library. Fascinating contemporary account
“Many there were which fled into the tops of high trees, and there were inforced to abide some three daies, some more, and some lesse, without any victuals at all, there suffring much colde besides many other calamities, and some of them in such sort, that through overmuch hunger and cold, some of them fell down againe out of the Trees, and so were like to perish for want of succour. Othersome, safe in the tops of high Trees as aforesaid, beholding their wives, children and servants, swimming (remediles of all succour) in the Waters. “
Other UK tsunamis include a 70ft high wave that hit Scotland 7,000 years ago, following a massive landslip in Norway.