So remember "The Abyss"? (James Cameron)... the aquanauts were living in a habitat that was pressurized at the bottom of the Mariana Trench or something. Was th

So remember "The Abyss"? (James Cameron)... the aquanauts were living in a habitat that was pressurized at the bottom of the Mariana Trench or something. Was that just done before he realized it was physically impossible for humans to live in that kind of hyperbaric situation...? Or is it possible at any pressure with the right gas mixture?