Or, as a Navy dive specialist is said to have commented upon being shown a rather haphazard piece of diving apparatus (before SCUBA):<font face="Verdana, Arial" size="2">Originally posted by lone wolf:
And in the last moments the ship vanishes right up it's own arse.
Rapidly followed by the series and the entire franchise.</font>
"Sir, what you have here is a Mod 1, Mk. 0 hypoduchenator rebreather ... you take a rubber hose, stick one end up your <ahem>, put the other end in your mouth, and start breathing."