The location in the Faroe Islands Is not Eidi but Bour.
In the novel this film is based on, Danielle Flinders is described as a mixed-raced woman. Her father is Australian and her mother is from Martinique, a country where 90% of the population is black. An excerpt from the novel says the following about Danielle; "In her complexion and variety of dress and habits and manners there was something of her mother's Creole background". Swedish actress Alicia Vikander (who is of 100% European descent) was cast for the role.
James McAvoy starred in multiple X-Men films with Michael Fassbender, who is married to Alicia Vikander.
This is the third time McAvoy played a soldier (Atonement and Band of Brothers) and the third time Vikander was in an ocean-centric film (Tulip Fever and The Light Between Oceans)
Based on the 2011 novel Submergence by J. M. Ledgard.