In article ,
Doug Winterburn wrote:

My physicist buddy that does torpedo testing says max speed for a
conventional torpedo is 55 knots, but supercavitating torpedoes are
capable of much higher speeds by essentially traveling in a gas bubble
and are therefore also not technically [water] displacement devices.

I'll simply suggest that _something_ is moving the water out of the way,
be it the torpedo body or the 'gas bubble'. Else an elementary fact
of physics is being violated. *OR* somebody has managed to implement
the tunnel diode at a macro scale. grin