Do you swim with your mouth open or closed under water?

Not sure I understand the question.  I breath out of both my mouth and nose when my face is in the water.  I continue to breath out until I turn my head for a new breath.  I sounds like maybe you are holding your breath.  I think you should work on continuous breathing while you swim.  I may be giving your bad advice though as I've never had any formal swim techniques training.

~Mike

I leave my mouth open in fresh water and try to close it and only use my nose in salt.  You should definitely breath smoothly and continuously under water, this will save you from exhaling when you turn your head.

As for fish, that is just another source of protein I don't have to take in on the bike. 

I breathe in and out through my mouth.  I've tried to breathe out through the nose, but I seem to end up getting water up my nose, don't know why that is, but if I breathe out through my mouth I don't get water up my nose.

Thing that's odd about my breathing, is that in the pool, I breathe every stroke in salt I breathe every three.

 As long as you are not swimming with a mouth full of worms this is not going to be a problem. Fish survive because they can out swim creatures that swim a lot faster than you. Now jellyfish, that's a different story. Of course keeping your mouth closed is not going to help you there. 

Swim mouth open or closed, just slightly exhale through your nose with your face in the water. Some of it will make it out of your mouth. However, if you are racing in the water ot sprinting in an workout, you want to use an explosive exhale to vacate your lungs of carbon dioxide befor inhalation.

Regardless of where I swim or how fast or how long, I always breathe out through my nose and mouth the entire time my face is in the water.  When my face is out of the water, I breathe in through my mouth.

I know some people just breathe out through the nose, but I don't see how...

skarl - 2008-06-22 9:31 AM I exhale thru my nose in the pool and the lake and inhale thru my mouth in an attempt to limit the amount of water I swallow. But since I usually have to pee by the end of the swim, not sure it helps much.

I feel bad for the guy behind you, "hey, did the water just get warm?".  *There's* an incentive to close your mouth when swimming.