The submarine forms an insular forgotten space, a chance to disappear, to explore, to discover.  However in this environment you are not free, the submarine forms an intricate life support mechanism resisting the immense pressure of the water around, sustaining life in the most inhospitable environment on earth.  The dangers of exiting such a machine at extreme depth are phenomenal, risking pressure, poisoning and the bends.  How does it feel to be within this machine, to be contained and held in this alien environment? How and when would you take your chance?  Would you make it?