It’s a big ocean out there. The Marine Corps’ push to return to its maritime roots and get more leathernecks out to sea on Navy ships means a brighter spotlight on some of those missions that haven’t routinely been done by units more attuned to the sandbox of combat. While the public might be more aware of operations to track and capture gun-toting hijackers and pirates or terrorists at sea, such visit-board-search-seize training (above photo) aren’t the only high-speed training Marines are getting to do. Just this month, after some training in San Diego, Calif., members of the 15th Marine Expeditionary Unit headed north to Ventura…