•
Emily Hampshire as Rose Mason: The oil company representative and scientist, and a fresh face on board the rig. •
Iain Glen as Magnus MacMillan: The leader of the crew and the
offshore installation manager of the rig. •
Martin Compston as Fulmer Hamilton, the radio and communications officer on the Kinlock Bravo crew •
Mark Bonnar as Alwyn Evans, an older and experienced crew member with an interest in history, archaeology, and reading (series 1) •
Rochenda Sandall as Cat Braithwaite, the medic on the rig •
Owen Teale as Lars Hutton, a crew member who's been stationed on the rig for a long time, and who begins to sow tension and division on the rig • Richard Pepple as Grant Dunlin (series 1) •
Calvin Demba as Baz Roberts, a young, relatively inexperienced crew member who wants to get off the rig (series 1) •
Emun Elliott as Alec "Leck" Longman (series 1) •
Abraham Popoola as Easter Ayodeji •
Stuart McQuarrie as Colin Murchison, the rig's cook • Molly Vevers as Heather Shaw • Dougie Rankin as William Johnson (series 1) • Nikhil Parmar as Harish, a survivor from Kinloch Charlie •
Mark Addy as David Coake, Pictor's research head • Neshla Caplan as Kacey, Cat's wife • Ross Anderson as Kyle Cameron (series 2), the Stac's diver •
Alice Krige as Morgan Lennox (series 2), Pictor's CEO • as Askel (series 2), the Stac's scientist •
Jacob Fortune-Lloyd as Darian York (series 2), an investor at Pictor, later becomes its CEO • Phil McKee as Bremner (series 2), Coake's assistant == Episodes ==