This film completely lacks any linear narrative. I would actually go so far as to say it is more a series of epic tableaus, similar to those that the Victorians used to elaborately stage, than an actual story. While the initial premise of two men left on an island lighthouse is the frame for the film, what follows is a kind of maelstrom of shifting perspectives, character explorations, and surrealistic nightmares.
In the same way that "The Witch" wanders from scene to scene providing us with a parade of indelible images, "The Lighthouse" is like Winslow Homer's nautical paintings and Fuseli's grotesque gothic sketches are interspersed and illuminated in some sort of manically swirling magic lantern.
The language of the movie and its faithfulness to the period is like nothing I have ever seen on film before. Never have filmmakers been so committed to meticulously re-creating a period and faithfully evoking the mood of an era.
I would be interested to see a film in which Mr. Eggers decided to devote more attention to his narrative, and took his audience on a journey rather than concentrating on imagery alone. I suspect that Eggers may be avoiding narrative progression intentionally and the he may enjoy having his readers create a gestalt out of the disconnected and often ambiguous relationship between what he shows us and the meaning behind these vignettes.