By Lucas Reilly - Mentafloss
Anders Franzén lived for shipwrecks. An engineer and expert on the naval warfare of the 16th and 17th centuries, he was especially obsessed with the old Swedish men-of-war that had once menaced the Baltic Sea.
When he wasn’t busy at his day job with the Swedish Naval Administration, he’d spend hours combing through archives in search of maps and documents, hoping they might reveal the location of Sweden’s great sunken warships.
And when he learned that one wreck might still be trapped, undiscovered, not far from his home in Stockholm, he was hungry to find it.
For five years, Franzén spent his spare time searching for the shipwreck. He had little luck. Trawling the waterways around Stockholm—what locals call the ström—with a grappling hook, Franzén's “booty consisted mainly of rusty iron cookers, ladies’ bicycles, Christmas trees, and dead cats,” he’d later recall.
But on August 25, 1956, Franzén's grappling iron hooked something 100 feet below. And whatever it was, it was big. Franzén gently lowered a core sampler—a tool used by oceanographers to get soil samples from the bottom of bodies of water—and retrieved a dark and soggy chunk of black oak.
The following month, Franzén's friend Per Edvin Fälting dived into the ström and see what was down there.