[PSUBS-MAILIST] concrete Submersible ?

["Marko Thiele" <marko.thiele@gmx.de>]

hi,

My Name is Marko Thiele and I'm new to this mailinglist. I just thought to
introduce myself. I'm from Germany and an structural engineering student at
the Dresden University of Technology.
The following question I got for you folks might not sound very smart, but
I'm serious and hope for an serious answer.
So here it is.....

does anyone of you know if anyone has ever attempted to build a Submersible,
Submarine or similar out of concrete ?
(yes, I mean indeed this rock like material)

If anyone knows something about this, or thinks he knows that this has never
been done, I would love to here from him.

 so long...
    Marko