Remarkable footage shows the moment that divers discover a tugboat's cook, who had lived underwater for three days in an air pocket after his vessel sank off the coast of Nigeria.

Harrison Okene, 29, was discovered by divers in a toilet compartment 30 metres underwater, 62 hours after the vessel overturned.

The video shows the diver discovering Okene for the first time, a moment that unsurprisingly startled them both.

When the Chevron-contracted Jascon 4 vessel sank off the coast of Nigeria all other 11 passengers on board the tug drowned, leaving Okene incredibly fortunate to survive.

"The rescue operation involving helicopters and other vessels swung into action almost immediately," DCN, the diving company that rescued Okene said in a statement.

"At that time, there was no trace of the crew members ... as internet reports about the accident continued to develop, the realisation grew among the divers that there could still be survivors of the Jascon 4, trapped in an air pocket."

Nigeria is the biggest oil producer in Africa and Chevron is a major operator in the country.