At the time of writing, the Wikipedia page for All is Lost has a section that reads nothing more than “A man is lost at sea and struggles to survive.” The only amendment I would make is adding that he wakes up to water rushing into the interior because of a collision with a shipping container, and even that is for specificity more than for elaboration; it’s probably fine as it is.
That means that what you make of Robert Redford’s journey is entirely up to you. You get a quick monologue at the film’s beginning, you very, very rarely hear the human voice after that, and when you do, it isn’t to voice fully-formed thoughts. The only backstory is an incredibly vague letter that opens the film. Why is Our Man (as Redford is credited) out at sea? Is he apologizing? What for? Who even is he? The film never attempts to answer any of these questions, and that’s its biggest virtue. All Is Lost doesn’t need contrived grandstanding to make a fight for survival potent and respects us enough to treat the protagonist as a human with regrets, guilt, and responsibility. He doesn’t need a kid to fight for and he isn’t a guy stuck-in-a-rut who gets the will to live knocked into him by incidental brushes with death. Like you or I, he is a human who wants to live.
To this viewer, All Is Lost is a religious allegory. There is no mention of God or spirituality, of course, and even looking for imagery would prove to be in vain until the very end of the film. Still Our Man’s struggles fulfill the basic questions that largely characterize and even inspired religion in the first place. He struggles with faith, unsure of whether or not he will be saved; he is confronted with his own mortality, doubtlessly wondering what would come next for him, and J.C. Chandor’s (Margin Call) compositions often times foreground the sky, giving us nothing to look at or think about aside from what lies beyond. Only when Our Man sends out a message—or rather a confession—in a bottle…I won’t spoil what happens next.
All is Lost could just as well be a parable for life in general (although at the end of the day, that largely amounts to the same thing). You are all alone, everything goes wrong, you miss a good opportunity (“that ship has sailed,” your friend might tell you), and you really just need a helping hand to get through. Or it could be something else entirely. Maybe it’s just a guy trying to survive.
The beauty of this is that it is all for the viewer. All is Lost never even thinks to offer anything more than exactly what it is. What you make of this struggle for survival is entirely up to you. The reason it works so well is because of Chandor’s simple but elegant compositions, the brilliant casting of Robert Redford, whose low-key mannerisms and demeanor is perfect for the part, and the sound design, without which the film would be largely ineffective. Without dialogue, and with no eye-popping sets, immersion depends almost entirely on sounding like you are right there on the boat or underwater, and the Leviathan-esque rapid-trips to and just beneath the surface pit the overwhelming quiet of a potential killer and the utter hopelessness of the supposedly habitable world against one another. Even with limited food, the weather ensures that drowning is the most likely possible outcome, and whenever Our Man falls below the surface, the sound, of course, instantly drops out. When he comes to, crashing waves and thunderstorms don’t seem particularly preferable. He could choose to let himself fall beneath a ring of fire that evokes, quite literally, Dante’s Circles of Hell, or he could rise to the heavens.
Not everything about All is Lost works. The opening monologue is not entirely necessary, and when Our Man has a quick, miniature meltdown, complete with screams, the moment is not convincing but rather a startling, ill-conceived moment of melodrama in an otherwise entirely low-key film. Additionally, the film never questions survival, faith, or aloneness but simply depicts them in their most stripped-down forms. There are minor qualms, such as the questionable use of the score (by Edward Sharpe and the Magnetic Zeros’ Alexander Ebert) and occasional shots that reach too suddenly for poetry (an underwater shot of a group of fish is the most egregious example), but the parable holds strong.
All is Lost has more than a few precedents, from Cast Away to Life of Pi to Gravity, but all of these films build up backstory as a way of investing us in the character. Paradoxically, this method can make the character considerably less compelling, as we root for them in terms of their story instead of for their sheer humanity. All is Lost strips away the surplus and proves that we don’t need a reason to care about people. We don’t even need much of a reward for investment, just the act of caring is enough.