Okene, wearing only his underpants, survived around a day in the four foot square toilet, holding onto the overturned washbasin to keep his head out of the water.
He built up the courage to open the door and swim into the officer's bedroom and began pulling off the wall paneling to use as a tiny raft to lift himself out of the freezing water.
He sensed he was not alone in the darkness.
"I was very, very cold and it was black. I couldn't see anything," says Okene, staring into the middle distance.
"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."
What Okene didn't know was a team of divers sent by Chevron and the ship's owners, West African Ventures, were searching for crew members, assumed by now to be dead.
Then in the afternoon of May 28, Okene heard them.
"I went into the water and tapped him. I was waving my hands and he was shocked," Okene said, his relief still visible.
He thought he was at the bottom of the sea, although the company says it was 30 meters below.
The diving team fitted Okene with an oxygen mask, diver's suit and helmet and he reached the surface at 19:32, more than 60 hours after the ship sank, he says.
Okene says he spent another 60 hours in a decompression chamber where his body pressure was returned to normal. Had he just been exposed immediately to the outside air he would have died.
"I don't know what stopped the water from filling that room. I was calling on God. He did it. It was a miracle."