A man has been attacked by a shark in far north Queensland after he "swam along" with it for a while, paramedics say.
The 21-year-old has been airlifted to hospital with "deep puncture wounds" after the shark suddenly bit him on the arm and shoulder as they swam near Clack Island off Cape York.
Queensland Ambulance Service said the man came across what he believed was a bull shark while diving for sea cucumbers after 12.30pm on Thursday.
"He swam along with it for a little while before it changed behaviour and attacked him," Flight Critical Care paramedic Valerie Hurlbatt said.
The man was able to get help, applying a tourniquet to stem the bleeding before being transferred to a larger boat who contacted emergency services.
A rescue helicopter left from Cairns for the long journey north, refuelling at Cooktown and flying another hour before landing at remote Clack Island.
QAS said the man was taken to Cairns hospital in a serious but stable condition with "non-life threatening injuries".
"He was very, very lucky it didn't sever anything critical," Ms Hurlbatt said.
"By the looks of it, it has missed the main arteries. However, he did lose a little bit of blood."
Clack Island is part of the Great Barrier Reef Marine Park, located at the tip of Cape Melville on the Cape York Peninsula.
Australian Associated Press