The late Paul Allen's underwater robotics are still achieving firsts in discovering long-lost warships. Vulcan's research vessel Petrel and its two robotic vehicles have discovered the Kaga, a Japanese aircraft carrier sunk during WWII's pivotal Battle of Midway. It's the first time anyone has found a Japanese carrier, Vulcan said, and also the most extensive search the Petrel team has conducted. The team spent several weeks combing an entire battlefield, covering an area of more than 500 square nautical miles -- it found the Kaga more than 17,700 feet underwater.
The search process was familiar, but arguably more necessary than ever given the scale of the project. An autonomous underwater drone (AUV) searched with preset criteria for up to 20 hours at a time, returning with data that could hint at ships or other unusual features. After that, a remotely operated vehicle dives down to verify any potential hits with live imagery. It's a slow process, but it's also far more practical than using a remote-controlled vehicle (let alone a crewed one) in these conditions.
While the discovery no doubt offers Vulcan some bragging rights, it also indicates that techniques like this could be vital for filling gaps in naval history. So long as there's enough left of a given ship to find in the first place, it might just be a matter of giving robotic explorers the time they need to search an area and solve a mystery.