In Dec. 2013, the AHT Jascon 4, a tugboat manned by a crew of 12, was struck by a rogue wave and sank into the murky waters off the coast of Nigeria. The vessel capsized quickly as it was swallowed up by the sea, taking the entire crew with it as it went.

Three days after the tugboat sank, a crew of divers was given the unenviable task of recovering the bodies of the 12 men that had gone down with their ship. The vessel had come to rest on the sea floor, just about 100 feet from the waves crashing overhead, and Tony Walker, the dive team’s crew leader, was monitoring his diver’s progress from a control room in his surface ship.

“We had already recovered four bodies,” Walker said, “So the anticipation wasn’t great that we were going to find anybody alive at that stage.”

It was at around that point that one of the divers, equipped with a camera recording footage from inside the sunken vessel, approached the closed bathroom door. What he found inside came as a shock to everyone involved; a survivor that had been trapped inside an air pocket on the ship at the bottom of the sea for three days, with no means to signal for help, and until then, no hope for rescue.

“The diver saw a hand in the passageway and assumed it was another body,” Walker told ABC News. “When the diver reached up to grab the hand, the hand grabbed the diver.”

The survivor turned out to be Harrison Okene, the ship’s cook. He had been in the bathroom of the ship when the rogue wave struck it, and as the vessel quickly sank into the sea, Okene scrambled to find a pocket of air to keep him from drowning. There, in the belly of the ship, he found a few feet of breathable oxygen, and remained there in the dark, with no supplies, until Walker’s team discovered him.

“I was there in the water in total darkness just thinking it’s the end. I kept thinking the water was going to fill up the room but it did not,” Okene said after his rescue. His skin was visibly peeling off from exposure to the salt water at the time.

“I was so hungry but mostly so, so thirsty. The salt water took the skin off my tongue,” he added.

Okene’s nightmare wasn’t only worsened by the pitch darkness, the cold, or the lack of fresh water. He also had to manage the emotional trauma of being aware that his dead crew-mates were around him, being eaten by the fish that had taken up residence in the sunken ship.

“I was very, very cold and it was black. I couldn’t see anything,” Okene said without looking at the camera. “But I could perceive the dead bodies of my crew were nearby. I could smell them. The fish came in and began eating the bodies. I could hear the sound. It was horror.”

According to Eric Hexdall, a nurse and clinical director of diving medicine at the Duke Center for Hyperbaric Medicine and Environmental Physiology, Okene’s unaware rescuers arrived just in time, as the pocket of air Okene had survived in was likely reaching dangerous levels of carbon dioxide buildup.

“If you’re trapped in something like that, your carbon dioxide levels will build to a toxic level before you use up the oxygen,” Hexdall said. He estimates that the air would have been breathable in a bubble of that size for approximately 56 hours before Okene would start to succumb to carbon dioxide poisoning.

“At 50,000 parts per million [of carbon dioxide particles], you see measurable signs of toxicity. At 70,000 parts per million, you lose consciousness pretty rapidly.”

Hexdall surmises that Okene would have started to feel the adverse effects of carbon dioxide poisoning after about 56 hours, and likely would have lost consciousness and died by 79. When rescued, Okene had already been trapped in the ship for over 60 hours.

Okene was led to a diving bell, which was able to return him to the surface and into treatment in a decompression chamber, where he would have to remain for another 60 hours. Okene, as well as a number of medical and diving experts, have all characterized his survival as something akin to a miracle, though his incredible luck hasn’t saved him from suffering the emotional consequences of such a traumatic experience.

“When I am at home sometimes it feels like the bed I am sleeping in is sinking. I think I’m still in the sea again. I jump up, and I scream,” Okene said, shaking his head.

“I don’t know what stopped the water from filling that room. I was calling on God. He did it. It was a miracle.”

Okene has since promised that he will never return to the sea, choosing instead to do his cooking on dry land.

Watch the video of his incredible rescue below.