Terrifying simulation shows how man survived 60 hours underwater after boat sank to bottom of ocean

A man miraculously survived two and a half days trapped in a bathroom at the bottom of the ocean in nothing but his boxers after waking up to use the toilet.

It has been 11 years since Harrison Okene defied death after his boat capsized 20 miles off the coast of Nigeria as water forced him into what would be the only room on the boat to have a pocket of air inside.

Now, a terrifying simulation has been created by the YouTube channel Brew that details exactly how the 29-year-old managed to survive 60 hours underwater on the seabed of the Gulf of Guinea, which is part of the Atlantic Ocean.

Harrison was working as a cook on Jascon-4, a tugboat back in 2013 - along with 12 other people - with the vessel purposed to stabilize an oil tanker.

One night, however, a colossal wave hit the tugboat, turning it and the crew inside upside down.

Being on the toilet - wearing only his boxers - when the freak wave impacted the boat, Harrison began to panic when water quickly began to fill the cubicle.

After managing to open the door, he emerged into the darkness but was able to see that the boat's propellers were up and the wheelhouse was down.

He then bumped into a handful of his colleagues, who battled with the boat's hatch as the water inside continued to rise.

However, the force of the water pushed him away from the exit and further into the vessel into another toilet, this one attached to the second engineer’s cabin.

Believing he was doomed, Harrison had no idea that this move had actually saved his life, with the bathroom unable to fill completely with water.

He was forced to cling to the base of the washbasin, keeping his head in the small pocket of air below the ceiling, which was actually the floor.

You can watch the YouTube video of the simulation here:

Harrison then accidentally broke off the door handle to the bathroom, still believing at this point that the main exit was his best chance at survival.

At this point, he had realised that the boat had actually reached the ocean floor.

“But I told myself, instead of panicking, you have to think of a way out," he later told the Guardian. "The air couldn’t go out of the boat completely. Some had to be trapped inside."

Harrison later managed to find two mattresses - stacking them on top of each other - so that he was able to stay above the rising water in his tiny little bathroom chamber.

"I tried to kill the fear in front of me," he said. "Because one thing that can kill you fast is fear.

"That panic that comes at you, it kills you before your real death comes.

"Because the moment you start panicking, you use too much oxygen."

After around 60 hours, with no food or water, and with minimal air remaining in his chamber, Harrison's prayers were answered.

A diving crew had been sent out to collect the bodies from the shipwreck, with Harrison - having noticed strange lights and hearing sounds - leaving his chamber to reach out to a diver, who subsequently saved his life.

The incredible moment was even caught on camera.

He was then taken from the divers’ bell to a recompression chamber where he would be forced to spend a further three days, being that he'd have died if he returned straight to the surface.

"Everything was normal. My temperature, blood pressure. I thought, that’s not normal," he later explained.

Stranger still, however, is that following the traumatic incident - of which he was the sole survivor - abandoned his initial fear of the sea and became a certified commercial diver in 2015.

And to top off an incredible story, it was the rescue diver who discovered him at the bottom of the sea that presented him with his diving diploma.