I was wondering: If someone managed to go really deep with an exposed butt (with a cork so water would not find its way in) (which leads to another question: if someone decides to go diving with an exposed butthole would water start to pour in after some time?) and proceeded to poop… would the pooped poop manage to float all the way to the surface? Or the water pressure would smash it into oblivion? Or maybe it would stay down there? yes, I am drunk.
When you sober up, the answer will be obvious.
Salt water or fresh?
Since the OP brought it up, can anyone recommend a good diving cork? I’ve just been using one I found in a bottle of Sauvignon blanc.
Let’s introduce Whale Shit into this discussion.
To address the factual questions in the OP…
It is possible to evacuate one’s bowels while underwater. For photo evidence you can do a Goolge search for an image labelled warhammer maneuver. I first encountered said picture over on the Scubaboard website. Don’t say you were not warned!
[spoiler]You really don’t want to see this!
Whether it floats depends in no small part on the fat content. If it is positively buoyant it will keep floating up until it reaches the surface. If negatively buoyant, it will sink until it reaches bottom. However, fish life might take an interest and prevent the excreta from going too far. Yes, fish will eat it.
The data point provided by said photo would indicate it did not remain contained in one piece, though that may not be a function of the pressure at which it was excreted.
No, water does not normally begin to penetrate an exposed butthole at the normal depths for recreational diving (down to 130ft or 40 meters) nor at " extreme" depths of technical diving (200-400ft or down to 120 meters). No cork is required.
Iggy
A perfectly reasonable, scientific response. Thx!
- I assume Whale Shit is lacking in fat content.
If they’re in an unpressurised, soft suit, everything should be fine - the human body is mostly water - so it doesn’t feel significantly ‘squeezed’ by water pressure (exceptions being any spaces filled with air - lungs, sinuses, ears, etc).
If it’s a pressurised/rigid suit/vehicle, then there’s just no real way to stick your bare arse out of the window and survive.
[Nancarrow’s shoulder devil]OP, I don’t see why you should take Iggy’s word for it. The scientific method dictates that there is only one way to definitively answer this question. And do it NOW, don’t wait for the alcohol to metabolise.[/Nsd]
[Nancarrow’s shoulder angel]Getting drunk! What a splendid idea! Especially as it’s just turning 9am where I am.[/Nsa]
<shameful admission>
I, uh… might have engaged in some empirical testing.
</shameful admission>
Well, I for one was impressed, as was my wine. Now, about the fat content of Whale Shit…
Apparently whale poop floats.
The internet truly has everything. While searching I found this nice page entitled “Do Whales Poop?”
It goes on to mention that whales “shut down” other biological systems while diving deep and apparently only poop in relatively shallow water. So perhaps there is a depth below which humans couldn’t poop in the Warhammer maneuver fashion?
Any discussion of whale poop would not be complete without mentioning that apparently whale poop can be very valuable. Ambergris seems to actually be produced in the digestive tract of some sperm whales and then pooped out if not already vomited up. It is used in perfumes.
Well, raise my rent, Iggy. You truly are a scholar and have the google-fu. So much for the adage, “Lower than Whale Shit.” Ignorance defeated, for all.
Depth doesn’t matter. If whales are shutting down a bunch of subsystems during deep dives, it’s only to conserve oxygen.
An increase in external applied pressure (as when diving) squeezes equally on all exterior surfaces of your body. Your body responds by exerting an equal and opposite pressure, which is felt all the way through your body. Trapped pockets of gas will compress as you descend. This can cause ear discomfort (typicaly resolved by performing the Valsalva maneuver), and may also cause problems for air pockes trapped in the sinuses and underneath dental fillings. Pockets of gas in your digestive tract will also compress, but this is not typically problematic; in the most extreme case, that gas would compress to almost no volume, and to your colon, it would merely seem as if it were empty. Solid and liquid matter are basically incompressible, and so would not appreciably change in volume under increased pressure.
Bottom line (no pun intended) is that increased ambient pressure would not cause a pressure differential across a diver’s anus; it should be no more difficult for him to defecate at X depth than it would be at the surface.
There’s your problem right there - Sauvignon blanc is a dry wine and requires a cork made for dry purposes. A much more appropriate cork can be obtained from a nice Port.
And don’t worry about anal portwine stains. The sea water will prevent those.
Reported for thread shitting. 
I have to confess: it was a screw cap.
Well done.
All of this talk about whale shit reminded me of an article I had read recently. But could I find it on the internet? No. And why? Because there are a blue million articles about whale shit out there. Even when I added “dog” to narrow it down, there were still too many to sort through.
It wasn’t a total loss. One article only had the whale shit at the end, so I learned that insect poop is calledfrass.
And did you know that whale feces floats for only about 30 minutes? Although I expect that depends on the species of whale and its diet.
Did I hear you say pics or it didn’t happen? Yeah, you said that. This is your fault.
I had no idea that there were so many research teams out there collecting. If you should happen to run across an article about a woman and her sniffer dog collecting above the arctic circle (in Alaska, I think), please post it. It will bring me a sense of closure.
The Master Speaks:
http://www.straightdope.com/columns/read/5/how-deep-is-whale-shit
A truly classic line.
Regarding whether you could poop underwater, even without what has been said above, it seems clear that you could. Catastalsis is responsible for moving feces through the intestine, and if peristalsis can allow you to swallow a banana while you’re hanging upside-down, the intestinal equivalent ought to allow you to excrete while preventing “backwash” or enema-by-water pressure.
You’re going to have to get the bottom half of your wet suit cleaned.