When you think about drones, you probably imagine flying, buzzing vehicles that take to the sky. But drones can go underwater, too. In fact, they’re very successful at this type of mission. Now, a drone called Hydrus has uncovered a massive shipwreck off the coast of Australia and using a technique called photogrammetry, was able to digitally “reconstruct” the boat. There are around 3 million shipwrecks in the sea, and the vast majority of them are unknown. Deploying a proper expedition to locate such a shipwreck, even if you know the approximate location, can be very costly. Traditionally, di…