Video: http://youtu.be/iB9leWklyiw
Is left control hard coded as some kind of turbo key? I don't see anything special bound that key in settings or in the arma3profile file and this works for everyone by default.
Secondary bug:
You need to continue pressing left control and running after you resurface until the "drowning blur" has faded. If you release control too soon you will die but if you wait long enough you live. Shown in the video during the second example.