Comment Re:No (Score 1) 263
Equal pressure on the inside and outside is effectively zero pressure. That's why you don't blow up like a balloon and pop when travelling from sea level to high altitude, yet your bag of Doritios might.
You don't need to pressurize the liquid on the inside, let the ambient pressure do the work. Off the top of my head, you'd only need something like a flexible diaphragm let the pressures equalize. Remember that liquids are virtually uncompressable so you you'd have very little displacement. The problem then becomes dealing with the parts that cannot be filled with liquid, such as batteries but now you're talking about much smaller structures and a hardened case may be more practical for them. Most electrical components don't have compressible space inside them that I can think of off the top of my head.
Speaking of pressure equalization and diaphragms, there's no reason you can't do this with air on the inside, you just have to have a large enough compression space for the air to compress into (i.e. an external air tank/bladder). So if the pressure at depth is 100 atmospheres, you'll need a sea-level compression space ~100 times the volume of space that your working equipment requires. Better make sure that air in there is very dry, though as there could be all sorts of effects due to water vapor condensing, etc.