"Hold the line, Riders."

"Riders" is a submariner's term.

Riders: Anyone onboard a submarine at sea who is not ship’s company. This could be sailors from other boats riding for qualification, shipyard folks (especially during sea trials), VIPs and/or media people, mission specialists such as Crypto Techs or “spooks,” and so on. Some of these guys really fit in and become part of the crew and you miss them when they return to their unit, others are simply “fuckin’ riders”.