For more than 220 years, dedicated treasure hunters have sought to unlock the mystery of Oak Island, located off the southern coast of Nova Scotia, Canada. Though it’s unclear exactly what they’re looking for (Pirate gold? Shakespeare’s lost manuscripts? A sunken Viking ship?), some have paid the ultimate price for their efforts: In 1961, four men died during an ill-fated excavation of the island’s famous “Money Pit.” As the search continues on Oak Island, explore six other elusive treasures that have captured the imaginations of archaeologists and fortune hunters alike over the centuries.