As he waited, 30m under the sea, water began rising in the cabin. Okene took two mattresses from the beds and sat on top of them, hoping to stay afloat.
Hungry, cold and tired, he heard loud noises as fish - he thought they could be barracuda or sharks - started thrashing around, fighting over something big. He feared it was the corpses of his colleagues, and armed himself with a plank.
"At that point I was very scared," he said. "I said, 'So this is how I am going to die? What would happen to my wife? I don't even have a child yet. What about my mother and everybody I love - so I will never see them again?"'
Describing the moment a rescuer found him, Okene said: "I touched his head and he was shocked. He was searching and I just saw the light, so I jumped into the water." Paul McDonald, a member of the rescue crew, said: "All on board could not believe how cool he was when being rescued."