HMS Thetis and HMS Thunderbolt The Royal Navy’s worst ever submarine disaster occurred on June 1st 1939, when brand new vessel HMS Thetis sank while undergoing final sea trials in Liverpool Bay. A tragic series of errors contributed to the disaster, not least of which was a layer of bitumen paint covering critical holes on the interior hatches of the torpedo tubes. While surfaced, the presence of this paint led the crew to believe the tubes were not flooded, and the hatches were opened. Now, both exterior and interior hatches of the No.5 torpedo tube were open. The sub’s forward compartments quickly filled with hundreds of tons of water, and in the hours of drama that followed only four men managed to escape. Ninety nine sailors and civilians perished, drowned or gassed by the build up of carbon dioxide inside the half flooded vessel. Later, a salvage diver also died after suffering a severe “bend”, bringing the total death toll to a hundred. Eventually, on the 3rd September 1939 - the same day war on Germany was declared - the Thetis was towed to Moelfre Bay in North Wales and beached. The remaining and horrifically swollen dead bodies were removed and buried with full naval honours. The following photographs show the drama in various stages: 1. Pride of the Navy: brand new ‘T Class’ boat HMS Thetis is launched. 2. Small Boats circle the exposed stern of the Thetis: 3. A diver prepares to descend to the now sunken vessel: 4. Relatives and friend wait for news, Cammel Laird's company secretary speaking: 5. Finally beached at Moelfre Bay, Anglesey: Photo Source HERE, text by me.