I had a friend who worked on a very deep sea drone. He told me that it was better to flood as much of the drone as possible to minimize the strength of the pre

I had a friend who worked on a very deep sea drone. He told me that it was better to flood as much of the drone as possible to minimize the strength of the pressure vessels they had to build. The one exception to this was the buoyant components, which had to be hollow to work. These were made of hollow ceramic spheres of exacting sphericity. A sphere provides maximum enclosed volume and strength for a minimum amount of structure, so was a good choice for the pressure vessel shape. They had to be so perfectly spherical to force the pressure to be balanced across the sphere and distribute the compression evenly. Not sure if this was the exact drone he worked on, but the spheres look like what he described. http://www.whoi.edu/oceanus/feature/floating-without-imploding http://www.whoi.edu/oceanus/feature/floating-without-implodi...