so what 
happens if we both 
swell at the same time? like 
two molecules in a compression chamber 


as a land or ship-based hyperbaric chamber to artificially reproduce those conditions under the sea (pressures above normal atmospheric pressure) for diving-related and non-diving medical applications

as a simpler form of submersible vessel to take divers underwater and to provide a temporary base and retrieval system in the depths;

The historically older open diving chamber, open diving bell or wet bell is in effect a large diving bell, utilising an the equivalent of a moon pool, to equalise internal air pressure and external water pressure automatically without the need, necessarily, to measure and control it. An air compressor or bottled compressed air is required to maintain the volume of the air as it becomes compressed with increasing depth, or to make up for oxygen depleted by the occupants' breathing and for carbon dioxide removed from exhaled air by a carbon dioxide scrubber system.

 This type of diving chamber can only be used  submersed , as the internal air pressure is directly proportional to the depth underwater 

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