Who knew that it would be so important to know how to operate a toilet? On a submarine, though, it is important to know how to operate everything. The German submarine U-1206 was launched in 1944.

Its first active patrol started in April 1945, but it didn't last long at sea. It sank after it's toilet was operated improperly.

The sub had a deep water high pressure toilet so that it could be used in large depths. While flushing our above-water toilets is extremely simple (a potty-training toddler can do it), these high pressure lavatories were extremely complicated to flush.

Special technicians had to learn how to operate them. While cruising off the shores of Scotland at a depth of 200 feet, someone misused the toilet causing the submarine to flood.

The captain was forced to surface and the sub was bombed by a British patrol. One man was killed by the bombing, three drowned and 46 were captured.