Based on a true story from 1984, The Deep follows the blue collar crew of the Breki, a fishing vessel working the shores near the volcanic Westman Islands. Comparisons to The Perfect Storm are invited immediately as we meet the men in the hours before their latest voyage. Snapshots of their home lives and alcohol-fueled nights at the bar, looking for love (or lust) before heading out on the dangerous mission. There's the sense of impending doom hanging overhead, as each man knows each time they go out could be their last. Most are mere archetypes and not fully-formed characters: one is a father; another is a young cook from the mainland; and one has a young wife and kids. 
We mainly follow Gulli (Kormakur regular Olafur Darri Olafsson), an overweight, veteran member of the crew who joins them in the early morning launch. The issue of Gulli's size is a factor right from the start, with easy jokes about his love of food and the need for the ship to have a good chef. But it becomes an even greater element later on, and leads to the incredulity of his feats. Kormakur matter-of-factly takes us through their regular routine out on the icy waters, dulling us (and the crew) into a false sense of security. They soon hit rough waters, and within a matter of moments the boat capsizes, sinking the vast majority of the men into the murky depths.
Gulli survives along with two others, but as the temperature drops and the waves continue to batter them, he's soon left to fend for himself. In a harrowing, improbable battle against nature and increasing hopelessness, Gulli attempts to make the miles-long swim to shore. It's a fight he nearly loses on more than one occasion, but through a combination of faith and determination, he survives the vast, inky seas only to face long stretches of steaming volcanic rock. Vintage flashes of Gulli's childhood memories cleverly build on his indomitable will, while also cluing us in to the volcanic eruption that will plague him on his trek.
Kormakur impressively uses no CGI throughout the film, relying solely on practical effects to capture the majesty and danger of the powerful ocean. The cinematography rivals some of the great naval efforts of Wolfgang Peterson, especially during the incredible shipwreck sequence. Through his lens we get a sense of his respect for the power the ocean wields, and how it's masked under a veil of great beauty. The naturalistic approach only adds to the enormity of Gulli's plight, while also making Olaffson's physical performance more of a wonder. Scenes where he is literally battered from rock to rock by crashing waves must have been devastating to endure, and one has to wonder how many weeks of recovery he had to through when filming was all said and done.As thrilling as the story is up to that point, it becomes significantly less so in the final act, as Gulli's survival is analyzed and scrutinized by a disbelieving public. Scientists, unable to understand how someone of his weight could perform such a superhuman feat, perform all manner of tests. At one point they dump him in an ice-cold pool with a group of Marines to see who can hold out the longest. It's Gulli's mother who cuts through all the statistics and numbers by asking the simple question, "How do you research a miracle?", and we're left to realize that there's never been an answer to all of the many amazing feats Gulli achieves along the way. Scientists come up with all sorts of theories, but it really seems to boil down to simple faith that kept Gulli afloat. Unfortunately, Gulli isn't a terribly interesting person when not fighting for his life, and watching him ride stationary bikes and answering reporters' questions is a bore. Because there's so little to Gulli's character, the film lumbers to a dissatisfying conclusion that, ironically, lacks any real depth.
