Kevin Lloyd says he freed himself from the jaws of a shark by stabbing it in the head and gouging its eye - while his friend grabbed its tail and tried to pull it off him.
The 24-year-old Kerikeri man was spearfishing near the Cavalli Islands in Northland with friends on Saturday when he was attacked by a 2m mako shark about 11am.
He said he had been in the water for about three hours and had just speared a kingfish when the shark "came out of nowhere" and latched on to his leg.
"I started stabbing it heaps with my knife and it didn't quite like that so it turned around and bit my hand.
"And then I was just trying to get my hand out of its mouth so I gouged its eye with my left hand - this is all while my mate's holding on to the tail of the shark trying to pull it off me.
"It was pretty lucky because my mate was there. I think it would have been way worse if he wasn't," he said.
The shark let go of his hand and swam off into the murky water.
"I was stunned. I couldn't believe it was happening. We dive with sharks all the time but this shark we hadn't seen."
Lloyd and his friend swam back to the boat, about 200m away, and applied first aid to his wounds.
They then picked up another friend who had been dropped off in a different spot and headed to Matauri Bay to meet emergency services.
Police attended the incident alongside ambulance staff.
Lloyd was transported to Bay of Islands Hospital where he was treated. The wound on his hand required 10 stitches but because of the nature of his leg wound - and the high chance of infection - it was decided to let it heal over time.
Despite the attack, Lloyd still managed to land the kingfish he had just shot.
"I'm pretty stoked about that. In the whole commotion, my gunline and the fish - the spear was through it - and that was wrapped around me. I started swimming back and it was still there so I grabbed it."
Saturday's dive was the first time Lloyd had been back in New Zealand waters since returning from the Pacific Islands with the Navy - where he works in communications.
He said the attack had not made him more cautious about getting back into the water.
Lloyd wanted people to know this was the action of one shark, not all.
"I see sharks quite often. Usually they just leave you alone. This is the first time I've genuinely been scared of a shark," he said.
The attack comes after Whangārei surfer Andrew Brough was attacked by a great white shark at Baylys Beach, near Dargaville, in October.
Department of Conservation shark expert and marine biologist Clinton Duffy said based on the location and the diver's description it was likely to have been a mako shark.
"They are very common all around Northland, particularly this time of year as the water warms up, and they particularly like offshore islands as well."
Duffy said mako were one of the most aggressive sharks and often attacked competitors.
"They are particularly aggressive, and due to their nature they'll bite anything they see as a competitor.
"It is likely it may have perceived the diver as a competitor, rather than food. Due to the murky water there is also a chance the shark mistook the diver for a kingfish.
"With other sharks, acting aggressively can make them back off, but with mako it can trigger an attack."
Spearfishing was always likely to attract sharks, Duffy said.
"The blood from the fish and vibrations from the spear gun are like dinner bells for sharks.
"You can always expect to find sharks where there are kingfish, too. They feed on the same sort of prey."
Despite their aggressive nature mako attacks were "very rare", and there had been no fatal attacks in New Zealand, Duffy said.
"As they are an offshore species people don't tend to come into contact with them, they are not a species swimmers are likely to encounter unless they are out in the open ocean."
Duffy said the spate of shark sightings and two recent attacks were nothing to be concerned about.
"Shark attacks remain very rare, two in a year is average, any more would be high for a year.
"This does not mean there are not sharks, just that they are not very interested in people.
"This time of year the inshore waters become very productive too, with lots of spawning, breeding, schooling of fish so there is a lot of food close to shore for sharks," Duffy said.
"And as the weather starts heating up and people head out to the beach we start seeing and encountering them. It is very typical."