Harrison - Underwater Link

: Because Harrison had been at that depth for so long, his body had become "saturated" with pressurized gases. Bringing him to the surface too quickly would have been fatal, so he had to be transferred to a diving bell and then spend another 60 hours in a decompression chamber. Life After the Depths

: He stood in freezing, chest-deep water, listening to the sounds of the ocean and the haunting silence of his 11 lost crewmates. Harrison - Underwater

South African saturation divers were eventually sent to the wreck, but they were tasked with recovering bodies, not finding survivors. : Because Harrison had been at that depth

If you'd like, I can find more from the divers who found him or details on the physics of the air pocket that kept him alive. South African saturation divers were eventually sent to

: With no food and thinning oxygen, his only sustenance was a single bottle of Coca-Cola he found floating in the wreckage. The Miraculous Rescue