One celebrated case involved the rescue of surfer Todd Endris in Monterey Bay, California, in 2007. A 15ft Great White shark attacked him, ripping the skin off his back 'like a banana peel', he said.
The shark then attacked again, swallowing his right leg and trying to wrench it off. Only his surfboard, which had become sandwiched between his thigh and the shark's lower teeth, prevented the loss of his leg.
But as the shark moved in to deliver thecoup de grace,a miracle happened. A pod of dolphins surrounded Todd and attacked the shark. Within moments, the shark was beaten back and swam away. The dolphins stayed with him until he was able to re-mount his surfboard and struggle ashore.
Louie Psihoyos, director of The Cove, was also saved by dolphins while diving in Polynesia. Unknown to Louie, a giant hammerhead shark had been stalking him and was preparing to attack. But then, out of the blue, a pod of dolphins he had been filming swam between Louie and the attacking shark.
'They saved my life,' he says. 'It is what people throughout history have witnessed, but I never expected to see it myself.'
But while we in the Western world see dolphins as friendly, 'cute' creatures, the Japanese Government and the nation's fishermen see them as little more than vermin. To them, killing dolphins and whales is no different to raising cows or pigs for slaughter.
'People say dolphins are cute and smart, but some regions have a tradition of eating dolphin meat,' says Toshinori Uoya, spokesman for the Japanese fisheries' department. 'Dolphin killing may be negative for our international image, but it is not something we can order stopped.'
In Taiji, many regard slaughtering dolphins as a normal part of daily life. They see the campaign against the hunt as an attack on their culture and traditions.
'And besides,' says, Mutsuyo Kaino, an 88-year-old housekeeper from Taiji, 'dolphin meat tastes so good.'
The Taiji slaughter is legal under both Japanese and international law, even though it occurs in a nature reserve. Although dolphins belong to the same family as whales, they are not protected by the international ban on whaling.
And while Japan openly flouts the ban, in the guise of so called 'scientific whaling', it is at least illegal and one hopes the country will eventually begin honouring the treaties it has signed up to.
No such treaties protect the 23,000 dolphins killed by Japanese fishermen each year - indeed, the dolphins are victims of the whaling ban.
When the whaling moratorium came into force in 1986, the Japanese authorities and fishing industry began slaughtering tens of thousands of dolphins. They did this to satisfy and maintain the Japanese love for whale flesh, which apparently tastes very similar to dolphin.
Within 12 months, the Japanese were killing more than 40,000 dolphins every year. Most were fed to children in school meals, with the rest being exported to China.
Ironically, recent scientific research suggests that the Japanese authorities might be endangering the health of their own children through this practice.