German submarine U-2331

German submarine U-2331 was a Type XXIII U-boat built for the German Kriegsmarine during World War II and intended for service against allied shipping in coastal waters. She was a brand new, high-technology electric U-boat which was lost when only one month old in a bizarre training accident in the Baltic Sea. Built at Hamburg, she was constructed at speed, as she and her sisters were seen as war winning weapons and thus vitally important to the German war effort.

Completed in September 1944, U-2331 was undergoing a fast-track working-up period in the Baltic under her commander Oblt. Hans-Walter Pahl under the observation of Klaus Vernier, a highly experienced U-boat commander and tactical expert. On 10 October, just 28 days after her completion, U-2331 dived and failed to surface in the sea off the Hel Peninsula. Four of the reduced crew (including the captain), escaped the sinking ship but 15 did not, including Vernier.

The Kriegsmarine conducted an investigation into the loss, at which it was revealed that either the captain or Vernier had ordered the submarine to submerge whilst travelling in reverse, thus unbalancing the boat and causing it to sink uncontrollably. A handful of men on the conning tower survived as the boat sank under them. The wreck was raised and taken to Gotenhafen, but the time submerged underwater had irreparably damaged the boat's systems, and the remains were scrapped.