Site of HMS Thetis beaching

What is it? 

The site of the wreckage of HMS Thetis, a submarine that beached Traeth Bychan in September 1939 

Where is it? 

Traeth Bychan, Marianglas, Ynys Mon, LL73 8PN 

What’s there? 

Traeth Bychan is inbetween Moelfre and Benllech. There is a café, public toilets, and a pay & display car park. The beach is used by walkers of the Anglesey Coastal Path, and the nearby Red Wharf Bay Sailing and Watersports Club 

Facts - 

▪ The vessel was lifted by a salvage rig using cables 15cm (six inches) thick and slowly moved to the beach here. It took several weeks to remove the bodies of the 99 sailors who had died inside the submarine. 

▪ Ninety-nine lives were lost in the incident: 51 crew members, 26 Cammell Laird employees, 8 other naval officers, 7 Admiralty overseeing officers, 4 Vickers-Armstrong employees, 2 caterers and a Mersey pilot 

▪ The submarine was built by Cammell Laird of Birkenhead and put to sea on 1 June 1939 for a day’s testing. 

▪ More than 100 people were on board, roughly twice the number in the normal crew for such a vessel. Some were officers in other submarines who wanted to see the latest technology for themselves. 

▪ Some small errors combined to cause the submarine to sink on its first attempted dive in Liverpool Bay. Only four men escaped from the submarine. 

▪ The bad luck continued weeks later, when a diver involved in the salvage operation died of “the bends” after getting into difficulties and surfacing too quickly. 

▪ The pressures of war dictated that Thetis was rebuilt rather than scrapped. As HMS Thunderbolt it sank several enemy ships before being wrecked by depth charges in the Mediterranean in 1943.