Why don't five feet snorkels work?

Question

I took a rubber tube and put foam on the end so it would float and took the other end into my mouth. When I went down 3 or more feet, I couldn't breath in, and the air was being sucked out of my lungs. I think what is happening here is the air in my lungs is more pressurized (from the water) than the air above the surface, so diffusion occurs (when a more dense substance, air, equalizes pressure with a less dense substance, air).Am I right?

Answer 1

basic physics

and for the record you can have a 20 foot snorkle you just need the power on the other side to draw the air in

Answer 2

More or less bang on with your thinking. The human diaphragm ( the part of your body that is responsible for inflating your lungs) isn't strong enough to do it's job against the water pressure being exerted on it much below 3 feet. We're built to breathe at one atmosphere of pressure. Not One atm plus.

That air in your lungs wasn't actually being "sucked" out, it was being pushed out. Your diaphragm just can't counter the ambient water pressure.

Scuba equipment gets over this by delivering air to a diver that is at the same pressure as the surrounding water pressure. No difference in pressure, no problem taking a breath. Just like breathing on the surface.

Answer 3

Just to expand a bit on the above answer:  As you go down deeper, the increased pressure makes it impossible to breathe.  Another problem with a long snorkel, is that the volume will increase, thus meaning you will be rebreathing the same area, though this could easily be overcome by breathing our your nose.

Deeper than 3-4 feet and you require some sort of aid to feed your air.