A robot submarine operated by researchers at the Woods Hole Oceanographic Institution (WHOI) discovered the remains of the San José, a Spanish galleon that was sunk more than three hundred years ago. The REMUS 6000, an autonomous underwater vehicle, discovered the wreck in nearly 2,000 feet of water off the coast of Cartagena, Colombia.

The location of the shipwreck had been an ongoing maritime mystery, speculated about by historians and searched for by treasure hunters for decades. The discovery was made in 2015, but the WHOI just recently received authorization to release the details about the discovery.

The 13-foot-long REMUS 6000 is designed for deep-water operations, with a maximum depth of 3.73 miles. The submarines can survey a large area using acoustic navigation, and high-resolution imaging systems on the bottom of the vessel can provide close-up details.

“The REMUS 6000 was the ideal tool for the job, since it’s capable of conducting long-duration missions over wide areas,” said expedition leader Mike Purcell.

The REMUS 6000 previously played a pivotal role in discovering the wreckage of Air France 447 in 2011, which crashed into the ocean and ended up on some of the most inaccessible seafloor on Earth. The submersible also participated in photographing the remains of the Titanic during a 2010 expedition.

The San José sank carrying a vast fortune in gold, silver, and emeralds, meant to fund the war effort led by France against England. The treasure is worth some $17 billion in today’s dollars.

Who owns the rights to the treasure has been the subject of an ongoing legal dispute between the Colombian government and an American salvage company, hence the delay in announcing the details of the discovery. For their part, the Woods Hole team is not involved in that particular squabble — they say they’re explorers, not treasure hunters.

More than three hundred years ago, the massive three-masted galleon ruled the ocean, armed with 62 bronze cannons engraved with dolphins. A flagship of the Spanish fleet, the San José ferried treasure from the New World back to Europe. It was able to best any pirates or rival ships that encountered it … until June 8, 1708, during the War of Spanish Succession, where the badly leaking Spanish ship went cannon-to-cannon with the British ship Expedition.

“The Expedition’s 32-pound cannonballs blasted through the heavy timbers of the San Jose’s hull at a distance of about 100 feet,” said a court filing for the salvage dispute that included an account of the battle. “The gunpowder which had been moved up from its lower hold to escape the leakage had ignited. Its explosion drove the hull of the San Jose down into the sea with a force so great it created a shock wave — a wall of water so high it came in at the Expedition’s gun ports.”

Colombian president Juan Manual Santos says that the discovery shows that the vessel did not explode, contrary to historical records. 600 people lost their lives when the ship sank.