the fleet marine force; infantry, combat support (aka, tanks, aav's, lav's, artillery), and close air support portions of the marine air wing. not the admin/paperwork guys hiding behind desks.
this pic is me in the driver station of my aav (amphibious assault vehicle), we're stopped at a road crossing waiting for the japanese mp's to show up and give us the go ahead to cross the trafficked civilian road to the training areas on the other side. taken 3 and a half years ago.