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.