A British diver separated from his boat off the coast of Australia has said he was lucky to be alive after being forced to swim miles back to shore - shadowed by a large tiger shark.
The spear fisherman, John Craig, was underwater off Western Australia state Friday when his boat was swept away due to engine problems and strong currents.
He told the BBC that sharks gravitated towards him because stress had raised his heart rate.
Mr Craig said: "I could feel my heart rate up, because I was panicking that I'd been left, after about five or ten minutes of this I put my head in the water to check I was still in the same place, and then at arm's reach, there was this huge four-meter tiger shark, I turned around and there was another fairly big sandbar whaler, which is another type of shark that you get here."
He told local media the tiger shark was "easily the biggest tiger shark I've been in the water with and that's saying something having worked as a dive instructor for over 10 years."
Terrified in the shark-infested waters near Shark Bay, he made the decision to swim back to shore.
"I have to admit that at this point I thought I was gone - four nautical miles out to sea with a huge tiger shark following me. I thought this was it, this is how I'm going to die," he said.
"The shark would disappear into the gloom then suddenly reappear behind me, just keeping pace with me behind my fins."
He spoke of how the shark pursued him, trying to kill him: "The shark didn't swim away, it actually followed me, so I started swimming towards the shore and the shark just kept pace behind me, so every time I looked back I just saw its huge head pointed at my fins, so I just kept my spear gun pointed towards my fins so it wouldn't get close enough to actually touch them, then it would disappear in the gloom then come down and come up below me and come from the sides...it was all because I was panicking.
"I've been a dive instructor for ten years, and I knew straight away sharks were there because my heart rate was up and I was panicking. After about three or four minutes of swimming it just accelerated then started swimming beside me going towards the shore. So for about 15 minutes it was just swimming with me."
Mr Craig kept his speargun pointed behind him as he embarked on a swim of "pure endurance", eventually losing the shark. He was later spotted by rescuers on a remote beach.
"It's an absolutely incredible story," Shark Bay Volunteer Marine Rescue commander Greg Ridgley told Perth's Sunday Times.
"He swam at least five miles in shark-infested waters... I just can't believe anybody could do that. It's such a massive effort, in that short timeframe too."
There have been 14 encounters off the nation's vast coastline this year, including the death of a 17-year-old girl mauled by a shark in full view of her parents in Western Australia.
Experts say incidents are increasing as water sports become more popular and baitfish move closer to shore, but fatalities remain rare.
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