That’s the hard part: if it’s fibreglass then it’ll crack, and you’ve gotta stop the plug from unplugging itself and letting all the air in

Unless you could get an acrylic plate wth a seal around the edge to go over the bath, got the bike pump working in reverse and reinforced the bath, you might stuggle even with some proper elbow grease

All it takes is either a multi million dollar human scale pressure chamber, or volunteering for some mad billionaires high altitude mach 5 manned vehicle tests

K doesn’t use the ° symbol ;)

And the increments of kelvin are the same as Celsius, they’re just at different points, where at 0K absolutely nothing is a gas or a liquid.

(Trying to decipher it right but you’re suggesting 0K be renamed -100°??

Depends on what altitude you’re at; get high enough and the depressurisation will boil the water in your blood straight out of every orofice available using only your body’s latent heat.