Gisborne's Wainui Beach is well known for its waves, and the competition among surfers for Gisborne's waves became unusually fierce this week.
At one stage a surfer feared for his life and opted to give up his wave to a rival with a far bigger fin - an orca.
"The fin was there, and it popped under, and it's other fin came up the side," surfer Michael Smith says. "It went underneath me, I was just like, 'I'm going to die.'"
However Karl McLeod from the Department of Conservation says the surfer was safer than he thought. There has never been a single fatal orca attack on a human in the wild.
"Orcas are very curious, highly intelligent and really social animals," Mr McLeod says. "So it's unsurprising that we have a number of encounters around the country, divers fishermen and stuff like that. Having said that, catching a wave with an orca right beside you, that's pretty exceptional."
Orca have been around since prehistoric times. They are sometimes known as the wolves of the sea, because they hunt in packs. However, if you happen to find yourself in the water with them, the best advice is tobut if you do happen to find yourself in the water with them, the best advice is to leave the area quietly, but not too hastily.