Its condition is pristine, but its identity is a mystery. For now, maritime archaeologists call it Okänt Skepp, Swedish for "unknown ship."
For 500 years, the Baltic Sea held in its depths a tall ship of the Renaissance era. Around the time the ship sank, Columbus was discovering the New World. His fleet vanished long ago. But the Renaissance vessel reappeared recently, remarkably well preserved in the icy Baltic waters.
The first hint of its existence came in 2009, when a sonar survey by the Swedish Maritime Administration registered an anomalous blip. Then, early this year, a robotic camera, employed