While sharks may not be the death machines that films like Jaws suggest they are, the idea of them actually saving someone’s life would surely be pure fantasy.
But that is precisely what one did according to a policeman from the Pacific island of Kiribati.
He claims that after being adrift in a wooden boat for 15 weeks, a shark alerted him to a nearby fishing vessel.
Toakai Teitoi’s ordeal began on May 27 when the 41-year-old flew in from his home island of Maiana to Tarawa, the capital of Kiribati, to be sworn in as a policeman.
Ironically, following the ceremony he watched a film about two men from Kiribati who died after being lost at sea.
Undeterred, he decided not to fly back to Maiana but to make the journey in a 15-foot wooden boat, instead, with his brother-in-law, Ielu Falaile, 52.
It should have taken just two hours.
However, they stopped to fish, fell asleep, and found themselves adrift, far from land, and dangerously low on fuel and liquids.
"We had food, but the problem was we had nothing to drink," he told Sky News.
Tragically, Falaile passed away on 4 July, with Teitoi turning to prayer to keep his hopes up.
In the days that followed a passing storm enabled him to fill canisters with rain water and he kept out of the sun by curling up underneath a seat at one end of the boat.
It was while he assumed this position on 11 September that he was awoken by a shark bumping and scraping against the hull.
When he stood up the six-foot shark swam off and he immediately spotted a fishing boat nearby.
He said: “He was guiding me to a fishing boat. I looked up and there was the stern of a ship and I could see crew with binoculars looking at me."