On the night of Dec. 12, 1978, the German barge carrier München issued a distress call in the North Atlantic. A week’s search collected four empty life rafts, but the ship itself was never found.

Two months later another ship discovered the München‘s starboard lifeboat. Its supporting pins had been bent, suggesting that a huge force had passed along the München from fore to aft, tearing the boat from its supports.

That boat had hung 20 meters above the waterline. What did the München encounter that night?