The pressure hull is the dry, sealed volume that resists the crushing pressure of the water column. Everything that cannot get wet — batteries, computers, the power bus — lives inside it.
We build it from a rolled aluminium cylinder with domed end caps, rated well past our working depth so the structure never becomes the limiting factor on a dive.
For engineers
Wall thickness is set by the buckling margin, not the yield margin: a thin cylinder fails by collapse long before the metal yields. We size against the critical buckling pressure with a safety factor of 1.5 over the rated depth.