One additional factor: at elevated pressure, oxygen becomes more abundant but also, eventually, more dangerous. Oxygen toxicity — a condition in which excess oxygen causes neurological and pulmonary damage — is a known risk for divers breathing compressed air at depth. Whether Okene’s oxygen exposure over sixty hours approached the threshold for toxicity is another question that the available reporting cannot definitively answer. The fact that he survived and reached the surface in good health suggests that the conditions were, at a minimum, compatible with long-term human survival.
## The Dive Team’s Discovery
The DCN Diving team arrived at the Jascon-4 site on May 28, 2013, approximately 60 hours after the capsizing. The company, a South African commercial diving firm that operates in the offshore oil and gas sector, had been engaged to conduct what was understood to be a body-recovery operation. The commercial diving industry’s offshore Nigeria operations are a significant business — Nigeria’s offshore oil sector generates contracts for diving, subsea engineering, and underwater work of various kinds, and South African diving firms have historically been significant players in the West African offshore market.
Jed Chamberlain, identified in reporting as DCN Global’s commercial manager, has been quoted in various accounts of the rescue. His description of the operation provides the outside-looking-in perspective on a rescue that, from the inside, was being experienced by Okene as rescue — but from the outside, had not yet been recognized as rescue.
The divers descended to the wreck expecting to find bodies. They found two, and then Nico van Heerden found a third presence in the dark water — a presence that, when it tapped him on the neck, did not behave like a body.