The German submarine U-1206 belonged to the advanced VIIC series, which was built to elude detection and effectively destroy enemy convoys.
It was a high-tech machine for its era, equipped with all the newest technology and onboard conveniences, including a cutting-edge bathroom.
German engineers had created a high pressure system that, instead of following the British practice of storing sewage in septic tanks on board the vessel, ejected waste directly into the sea, saving valuable space and weight. The system, however, was only effective when the sub was on or close to the surface, which was not ideal if you were submerged for extended periods of time, which was frequently the case during times of war.
Karl-Adolf Schlitt, captain of U-1206, discovered for himself during a fateful trip to the restroom on April 14, 1945, that it was also quite difficult to use.
Just nine days had passed since Schlitt and his crew embarked on U-1206's maiden voyage when a bathroom trip went horribly wrong.
Captain Schlitt made a call for assistance after being unable to figure out how to use the flush mechanism. Sadly, the engineer who assisted him turned the wrong valve by mistake, causing the cabin to fill with a mixture of seawater and human waste.
Following the foul cocktail's leak into the submarine's battery compartment, which was located directly below, a chemical reaction started that resulted in the release of lethal chlorine gas.
Captain Schlitt, who had no other choice, gave the order to blow the ballast tanks and head for the surface. Torpedoes were fired from the U-boat to increase buoyancy and shed extra weight.
But as U-1206 emerged from the depths, a Royal Air Force patrol spotted it and started firing. Captain Schlitt ordered the U-boat to be scuttled and any classified materials on board to be destroyed as the crew scurried for the dinghies.
Four crew members drowned out of the 40 people on board. The rest were taken as war prisoners. Before being captured, some of the men made it through the dangerous ten miles to the coast of Peterhead.
According to Captain Schlitt's official statement, "I was in the engine room when there was a water leak at the front of the boat. I now know that a mechanic had attempted to fix the forward WC's outboard vent.
"Despite severe flooding, the engineer who was in the control room at the time was able to make the boat buoyant and surface.
"At the same time, sea water was covering the batteries. The boat began to fill with chlorine gas.
"At that point, neither of us could move nor dive. British planes and patrols eventually found us at this point. I allowed the boat to sink.
A group of divers descended to a depth of 86 meters in May 2012 to examine the U-1206's wreckage. The submarine, which was discovered 12 miles off Cruden Bay in Aberdeenshire, was said to be in excellent shape despite having been submerged for more than 60 years.
At the age of 90, Captain Karl-Adolf Schlitt passed away in 2009.