A man has serious leg injuries and is in a critical condition after a shark attack in the far north of Queensland.

The 26-year-old was attacked while spear-fishing off Australia's Great Barrier Reef at about 10.30am local time on Saturday.

He was bitten repeatedly while diving near Hinchinbrook Island off the coast of Cardwell, according to Queensland Ambulance Service supervisor Ange Timmins.

His friends were able to bring him by boat to the town of Cardwell, where ambulance workers stabilised his condition.

The three friends were praised by the officer in charge of the Cardwell ambulance station, Martin Taylor.


He told Nine News: "From what I've been told he was in the water, he's been hit, they've heard a noise and they've dragged him in as soon as they've realised what's gone on."

Mr Taylor said the three friends pulled him into their boat and one of them, an ex-military serviceman with first aid training, tied a tourniquet high up on the man's thigh to stop the massive blood loss.

"The initial actions by the three friends have definitely saved this gentleman's life," he said.

The man is in a critical conditions in a hospital in Cairns.

It is believed the man was bitten by a bull shark or a tiger shark.