A 25-year-old man has made a lucky escape after he was bitten by a shark while spearfishing in remote waters off the Northern Territory.

WARNING: This story contains a graphic image.

Karl Waters sustained deep lacerations to his right arm when the whitetip reef shark moved to take his catch but latched onto Mr Waters' arm instead.

"He's trying to bite the fish and just ended up with my arm in his mouth," he said.

Map Umbakumba is a remote community in the NT.

The Alyangula resident set out with a friend early yesterday. Around lunchtime he was diving about 12 kilometres out to sea when the attack occurred.

The experienced fisherman said he quickly surrendered the catch before taking stock of the damage to his arm.

"I could see that he hadn't hit any of the main arteries or anything on the inside of the arm, so I sort of relaxed a little bit straight away then," he said.

"I gave my hand a little bit of a wiggle, made sure that he hadn't severed any tendons, and shouted out nice and loud to my mate who was in the boat at the time."

His friend raised anchor as Mr Waters swam back, and they worked quickly to bandage the wound and stem the significant bleeding.

CareFlight sent a fixed-wing aircraft to retrieve Mr Waters. ( Supplied: Careflight )

'He's very lucky'

Isolated in remote waters, Mr Waters was calm and collected as he mapped the next move.

The issue was to make it quickly back to shore.

But the men were of phone range, and had to resort to using a radio to contact nearby boats — one of which still had reception.

Craig Garraway from St John Ambulance said the man's injuries were minor, but communication issues complicated what happened next.

"This is all out in the ocean a long way from Darwin, so everything was done by sat phone; communication [was] very difficult," he told ABC Radio Darwin's Jolene Laverty.

"[He had] only minor injuries to the arm so it wasn't a serious attack, but obviously at the time with the poor communications we had to start planning for the worst."

The bite left Mr Waters with deep lacerations to his right arm. ( Supplied: Karl Waters )

Staff from the nearby Umbakumba health clinic treated Mr Waters after he was rushed back to land, before a CareFlight aircraft retrieved him about 1:00pm.

Northern operations manager Jodie Mills said he was admitted to hospital in Darwin in a stable condition where he was assessed by surgeons and discharged early Monday.

"He had some deep lacerations that just needed to be looked at at Royal Darwin Hospital," she said.

"We brought him through and thanks to the quick aid of his friends, undertaking first aid at the scene, and also the Umbakumba nurses who met the young man at the boat ramp, it was not nearly as bad as it perhaps could've been."

"He's very lucky."

Spate of attacks

The shark attack is at least the third in remote Northern Territory waters in recent months.

In September, a 17-year-old sustained knee injuries after he was attacked by a bull shark off Groote Eylandt.

The Alyangula man says he's keen to get back in the water. ( Supplied: Karl Waters )

Then in November, another 17-year-old was lucky to keep his arm after he was bitten by a shark while spearfishing off the coast of Arnhem Land.

It prompted local spearfishers to warn on social media that recent numbers of sharks in the area had been "the worst in years".

But Mr Waters remained undeterred. He said swimming alongside sharks was part of the risks spearfishers took.

"Every now and again you have an incident like this where they're trying to get the fish and you've got the fish a little bit too close to yourself and they accidentally get a hold of you instead of the fish," he said.