Dave Cannell wrote:

Try taking a plastic down to 100' under water then filling it with air
from your regulator and closing the cap. It certainly does 'puff up'
when you return it to the surface. BTW - So does a diver if they forget
to exhale on the way up 8-(


On our deep sumbmersible they frequently take items down and shrink them. 16oz Styrofoam
cups become doll sized. Of course we're talking DEEP submersible.

--
Tailgunner