I've done this with a tube as a kid and get what your saying. But would a goat skin underwater be the same? The tube example is because of the pressure differen

I've done this with a tube as a kid and get what your saying. But would a goat skin underwater be the same? The tube example is because of the pressure difference. Having a bladder underwater the air would easily come out to breath. IMO the harder thing would be getting the bladder to stay underwater, especially at the picture size, that would have a heap of buoyancy to offset.