The Nigerian cook survived by breathing an ever-dwindling supply of oxygen in an air pocket. A video of Okene's rescue in May that was posted on the internet more than six months later has gone viral this week.
As the temperature dropped to freezing, Okene, dressed only in boxer shorts, recited the last psalm his wife had sent by text message, sometimes called the Prayer for Deliverance: "Oh God, by your name, save me. ... The Lord sustains my life."
To this day, Okene believes his rescue after 72 hours underwater at a depth of 30 meters (about 100 feet) is a sign of divine deliverance. The other 11 seamen aboard the Jascon 4 died.
Divers sent to the scene were looking only for bodies, according to Tony Walker, project manager for the Dutch company DCN Diving.
The divers, who were working on a neighboring oil field 120 kilometers (75 miles) away when they were deployed, had already pulled up four bodies.
So when a hand appeared on the TV screen Walker was monitoring in the rescue boat, showing what the diver in the Jascon saw, everybody assumed it was another corpse.
"The diver acknowledged that he had seen the hand and then, when he went to grab the hand, the hand grabbed him!" Walker said in a telephone interview Tuesday.
"It was frightening for everybody," he said. "For the guy that was trapped because he didn't know what was happening. It was a shock for the diver while he was down there looking for bodies, and we (in the control room) shot back when the hand grabbed him on the screen."
On the video, there's an exclamation of fear and shock from Okene's rescuer, and then joy as the realization sets in. Okene recalls hearing: "There's a survivor! He's alive."
Walker said Okene couldn't have lasted much longer.
"He was incredibly lucky he was in an air pocket but he would have had a limited time (before) ... he wouldn't be able to breath anymore."
The full video of the rescue captured by divers was released by DCN Diving after a request from The Associated Press. Initially, a shorter version of the rescue emerged on the internet. The authenticity of the video was confirmed through conversations with DCN employees in the Netherlands. The video showing Okene was also consistent with additional photos of him on the rescue ship. The AP also contacted Okene on Tuesday who confirmed the events.
Okene's ordeal began around 4:30am on May 26. Always an early riser, he was in the toilet when the tug, one of three towing an oil tanker in Nigeria's oil-rich Delta waters, gave a sudden lurch and then keeled over.
"I was dazed and everywhere was dark as I was thrown from one end of the small cubicle to another," Okene said in an exclusive interview after his rescue with Nigeria's Nation newspaper.
He groped his way out of the toilet and tried to find a vent, propping doors open as he moved on. He discovered some tools and a life vest with two flashlights, which he stuffed into his shorts.
When he found a cabin of the sunken vessel that felt safe, he began the long wait, getting colder and colder as he played back a mental tape of his life - remembering his mother, friends, mostly the woman he'd married five years before with whom he hadn't yet fathered a child.
He worried about his colleagues - 10 Nigerians and the Ukrainian captain including four young cadets from Nigeria's Maritime Academy. They would have locked themselves into their cabins, standard procedure in an area stalked by pirates.
He got really worried when he heard the sound of fish, shark or barracudas he supposed, eating and fighting over something big.
As the waters rose, he made a rack on top of a platform and piled two mattresses on top.
According to his interview with the Nation: "I started calling on the name of God. ... I started reminiscing on the verses I read before I slept. I read the Bible from Psalm 54 to 92. My wife had sent me the verses to read that night when she called me before I went to bed."
He survived off just one bottle of Coke, all he had to sustain him during the trauma.
Okene really thought he was going to die, he told the Nation, when he heard the sound of a boat engine and anchor dropping, but failed to get the attention of rescuers. He figured, given the size of the boat, that it would take a miracle for a diver to locate him. So he waded across the cabin, stripped the wall down to its steel body, then knocked on it with a hammer.
But "I heard them moving away. They were far away from where I was."
By the time he was saved, relatives already had been told the sailors were dead.
Okene kept faith with the psalm he recited, that promises to "give thanks in your name, Lord," at a service at his Redeemed Christian Church of God.
He was rescued by a diver who first used hot water to warm him up, then attached him to an oxygen mask. Once free of the sunken boat, he was put into a decompression chamber and then safely returned to the surface.
Video of Nigerian cook's rescue