A TUG boat cook managed to find an underwater air pocket after his vessel sank off Nigeria's coast and survived nearly three days before being brought out alive, rescuers and his family say.

Of the 11 others who were aboard the tug when it sank in rough seas on May 26, 10 have been found dead and one remains missing. The search operation has since been called off.

Okene Harrison, 29, managed to squeeze into a compartment after the Chevron-contracted tug sank and settled upside-down 30 metres underwater. The Nigerian was brought to the surface after 62 hours.

"The rescue operation involving helicopters and other vessels swung into action almost immediately," marine and energy industry specialists DCN, whose divers eventually rescued Harrison, 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."

Divers from the firm, whose operations are based in the Netherlands, working on a project some 17 sailing hours away were eventually ordered to head to the accident site.

"Once at the accident site, the divers discovered that the wreck was upside down, and the cook on board the Jascon 4 was indeed trapped in an air pocket in a still intact compartment," DCN said.

"After 62 hours trapped in the air pocket, he was brought to the surface safe and well by the divers from DCN."

A man who identified himself as Harrison's cousin, Maxwell Ewoma, told AFP by phone that Harrison had been taken to the southern city of Warri.

He said the cook was doing well considering the circumstances and that doctors had ordered him to rest.

"He is doing fine," Ewoma said. "He needs rest. He's still kind of recovering from the shock."

The tugboat had sunk off southern Nigeria's Escravos, the site of a Chevron oil terminal. Chevron had said that heavy ocean swells caused the tug to capsize.

According to the operator, West African Ventures Limited, the tug was involved in towing a tanker at the time.

Nigeria is Africa's biggest oil producer, with Chevron among the major operators in the country.