A Deep Sea Vehicle (DSV) like Trieste or Limiting Factor or now Fundouzhe have control thrusters, ballast that has to be dumped, and other equipment to operate the DSVs.
But the pressure hull is a solid sphere minus the porthole windows and a hatch?
How does the pilot control these systems? Is there some conduits cut through the pressure hull? Optical penetrators could be used but how does this not compromise the integrity of the pressure hull? How else might it be done?