On Mon, 10 Sep 2007 15:40:31 +0200, Marc Heusser
alid wrote:

Cold shock response begins below 25°C and peaks at 10-15°C.
On cold shock: "...However, if they abandon ship into cold water, unless
they are mentally and physically prepared for the cold shock, are
protected with a survival suit, a lifejacket and a spray hood, they may
drown in the immediate abandonment due to the inability to control
breathing in the first three minutes of immersion.

Having been in that situation once as a teenager, I can verify just
how serious it is. Until you acclimate over the course of a minute or
two it is physically impossible to take a complete breath of air.