Somewhere in the Indian Ocean ("1700 nautical miles from the Sumatra Straits"), we see an abstract image of an object floating in water. Our Man (Robert Redford) narrates:
"13th of July, 4:50 p.m. I'm sorry. I know that means little at this point, but I am. I tried. I think you would all agree that I tried. To be true, to be strong, to be kind, to love, to be right, but I wasn't." And I know you knew this, in each of your ways. And I am sorry. All is lost here, except for soul and body, that is what's left of it, and a half day's ration. It's inexcusable, I know that now. How it could have taken this long to admit that, I'm not sure, but it did. I fought to the end. I'm not sure what that is worth, but know that I did. I've always hoped for more for you all. I will miss you. I'm sorry."
The film cuts to eight days earlier, as Our Man wakes up to find his sailboat, the Virginia Jean, a Cal 39, taking on water. He goes out on deck to see the boat has hit a detached shipping container filled with sneakers, leaving a yard-long hole in his high starboard side. He goes below to get a sea anchor and ties it to the container. The anchor pulls the container free from the sailboat. He steers the boat back to the side of the container and jumps onto the container to go retrieve his sea anchor. He then steers his boat away from the container for good.
Our Man checks the electronics on the boat and discovers that they do not work. He retrieves a box filled with fiber glass patch materials and mixes up a batch and starts patching the hole. He uses a knife to carve a piece of wood until it can fit in the manual- hand-bilge pump hole, as he has lost the lever for it. He starts pumping out the water from below deck. That night he sleeps in a hammock, above the water remaining in the boat.
The next day he continues patching the hole in the side of the boat and pumping more water. It's slow, exhausting work. He pulls out the radio equipment and pours bottled water on the interior of the devices to remove conductive sea salt from them. He sets them out to dry on deck.
The next day, he's able to complete cleaning the cabin with a sponge and mop. His fiber glass patch seems tentative, but at least keeps water out. He drags one of the boat's service battery on deck and hooks it to his radio. The radio does not work. He consults his navigation charts. He goes below and as he's looking through a book on celestial navigation, he hears someone speaking on the radio. He hurries back up on deck and makes an SOS call. It doesn't appear to work before the radio goes dead.
Later, he has a couple of stiff drinks and begins fixing a meal. It begins to rain. He goes out on deck and enjoys washing off in a brief rain. He eats a pasta dinner, reads some of a book using a head lamp, and goes to sleep.
The next day he hoists himself high up the mast in a bosun's chair, and discovers a disconnected antenna lead. He reattaches the lead but, while at the top of the mast, sees an oncoming tropical storm. He immediately descends to make preparations for it. He packs things away and even takes time to shave.
When the storm arrives, he runs before the wind under bare poles for a while, until he determines that approach is too tiresome and dangerous. He returns below deck to put on a rain suit. He intends to bring the boat into a hove-to position and puts on a safety harness and starts crawling to the bow to hoist the storm jib. Suddenly, a large wave hits him and he is thrown overboard. He manages to hang on and pull himself back on board, returning to the cabin where he vomits sea water and briefly collapses.
The boat starts to list heavily, then capsizes, rolling completely over. He goes back out on deck and throws the sea anchor out. The boat does another 180 degree roll, knocking him overboard. He makes his way along the mast and gets back on deck just before the boat returns upright. The main mast has snapped and most of the equipment on board is destroyed.
He cuts the mast loose, then goes back into the cabin and sees that the fiberglass patch has started leaking again. The boat lurches and he strikes his forehead on the bulkhead and falls unconscious. When he wakes, the cabin has about two feet of water in it, with more gushing in.
He grabs the bag containing a life raft and takes it out on deck. After tying the raft to the railing of the sailboat, he tosses it overboard and pulls the rip cord, causing the raft to self inflate. He pulls it close to the boat and jumps on board. He pulls the roof of the raft up and around and zips it closed. He rides out the rest of the storm in darkness.
The next day he awakens in the raft, which is tethered to the boat that is now is half-submerged. He pulls on the rope and brings the raft up next to the boat. He climbs onto the boat and looks things over. He lowers himself into the flooded cabin and gathers some canned food, fresh water and a few other items. He is leaving, but remembers something else he wants and pulls the raft back to the boat and goes back into the cabin, diving under the water and retrieving a white cardboard box. He then starts tending the wound to his forehead, until he realizes that the boat is going under. He returns to the raft and watches the Virginia Jean sink.
He opens the white cardboard box, which contains a sextant and a card. He tosses the card aside without reading it. He then refers to an instructional manual and tries using the sextant and navigational maps to determine where he is.
He wakes after sleeping to find sea water has seeped into his raft. He starts using a rag to mop it up and wring it out over the side.
He figures his best hope of being found is to make his way over to the shipping lanes. From his readings, he is heading north by northwest, toward a shipping zone he sees on the map. Another storm moves in. The storm capsizes his raft. He unzips the cover and goes out to pull the raft back upright. Back inside, surrounded by wind, rain, and water, he closes his eyes and covers his ears.
The next day he uses a hand pump to re-inflate the raft and continues bailing water out of the raft. He finds that his jug of drinking water has been contaminated by seawater, after which he gets emotional and emits a drawn out, "Fuuuccck!" He has a thought and cuts open the water jug and uses a plastic bag to make a freshwater still.
Our Man is exposed to the elements, becoming dehydrated and numb. His still works and he gets a little water to drink, savoring it. He maps out that he is in the shipping lane now and he begins looking intently along the horizon. Seeing nothing, he naps. When he wakes, he sees a cargo ship and lights a flare, waving his arms and yelling for help, as the ship passes by very close. It keeps on moving and disappears.
The next day, he finally gets a tug on his fishing line, but just as he is about to pull in a fish, a small shark grabs it at the surface. Many sharks are swimming under his raft. That night, he wakes up to find another cargo ship passing closely by, almost right on top of him. This time he fires off two aerial flares, but again, the ship keeps going and disappears.
On the eighth day, he charts that he has now moved north out of the shipping lane and back to open ocean. He is also out of food and has very little water and cannot hope to survive much longer. He writes the message that he narrated at the beginning of the movie, puts it in a jar, and with some hesitation, he tosses it into the water.
That night, he sees a light in the distance, possibly another ship. He is out of signaling devices, but tears blank pages from his journal and a book to create a signal fire in the empty water jug. As he adds more paper to the fire, he loses control of it and the flames consume his raft. He falls overboard. Treading water, he looks up to the heavens, then stops swimming and lets himself sink, watching the raft burning on the surface above him.
As he sinks, he sees the hull of a boat with a search light approaching his burning raft.
Our man swims up to the surface, and a hand reaches down to him.