Built in 1921, the København was the world's largest sailing ship at the time, with sails spanning an impressive 56,000 square feet. This Danish five-masted barque was equipped with a diesel engine that could propel it at 6 knots and featured reversible propeller blades controlled from within. The "Big Dane" was a floating classroom for eager cadets dreaming of seafaring glory.

In 1928, the København set sail from Buenos Aires to Australia and simply vanished. The last radio contact on December 22 reported "all is well." Then... silence. Theories abound about its fate. Did it hit an iceberg? Capsize in strong winds? For years after, there were tantalising reports of ghost ship sightings and mysterious wreckage.