What is the exact exhaling underwater in freestyle?

you can exhale more out of your mouth, but more controlled out of your nose. I would tend to think most people use the nose because of the control issue. Plus, when you get in open water, breathing out your mouth requires you to open your mouth and risk getting that nasty water in there. Personally, I exhale prob 90% out of nose. Try a few laps using one, then a few more using the other. See what feels most confortable and natural.

I think I do a little of both, but mainly out my nose. Mainly, you want to exhale underwater so that you are ready to inhale as soon as you turn your head to breathe and so water doesn't go up your nose, especially on flip turns if you do them.

It is Ok to exhale out of your mouth, nose or both. The main trouble of exhaling out the mouth only is a syphon (siphon) action through the nose. To make it easy I would suggest nose and mouth. The breathing action should be done just like you breathe when you are walking or jogging. A lot of swimmers are concerned with getting every bit of air out, I do not, I just try to breathe steadily.

Thanks guys for the advices! I will put this into practice. I really appreciate your help. :bouncing: