The Skandi Arctic is a diving support vessel working the North Sea oil fields off Norway, and this film goes aboard to show how saturation divers survive weeks of work on the ocean floor. Crews live in pressurized chambers for the duration of a job, breathing a helium mix and only decompressing once at the very end, because surfacing early would kill them. Divers are shuttled to the seabed in a diving bell, working on platform legs and pipelines in freezing water while the ship above holds position using dynamic positioning thrusters instead of anchors. The film walks through the ship's systems: the chamber complex, the moon pool, the control rooms tracking gas mixtures and pressure, and the support crew whose job is keeping the divers alive rather than doing the diving themselves. It is a close look at one of the more extreme trades in offshore engineering, built around the ordinary-sounding fact that these workers cannot simply come up for air.