An Italian university student has shared a confronting video showing the aftermath of a horror shark attack in Queensland that led to him losing half his leg.

Matteo Mariotti, 20, was attacked while snorkelling at the quiet fishing hamlet of 1770, about 130 kilometres south of Gladstone, on Friday.

The student from Parma, Italy, said he started filming because he did not think he would survive the gruesome encounter.

“I wanted to say goodbye,” he said.

The shark ripped into Matteo’s lower leg not long after he entered the water, savagely tearing into the flesh.

In the footage, the sea can be seen turning a foreboding shade of red as Matteo screams and thrashes while losing a lot of blood.

“I tried to widen that big mouth and with difficulty I freed my leg, even though from the knee down I could tell there was nothing left,” he said.

Matteo frantically thrashed back to the beach where his friend and diving instructor, Tommaso Agosti, dragged him onto the sand.

Tommaso attempted to stop the bleeding and keep Matteo calm until paramedics arrived.

He was rushed to hospital to undergo emergency surgery, however doctors were unable to save his leg and it was amputated below the knee.

Matteo’s friend Tommaso drags him out of the water at 1770. Photo: Instagram

Matteo told Italian television the shark had let go after biting his foot, probably because his snorkel fin was in its mouth.

“The shark stopped probably because it ingested my fin.”

Smiling from his hospital bed, Matteo said he thought the attack was the end of him.

Matteo had been in Australia since November 2022, studying marine biology.

He had gone to the water to seek solace after learning his grandfather had passed away the day before.

“I really thought I couldn’t make it,” he told Italy’s Gazzetta Di Parma.

Matteo Mariotti has been in Australia since 2022. Photo: Instagram

In notes accompanying the video on Instagram, Matteo said he began recording because he did not think he would survive.

“I played this video a few moments after the last bite. I wanted to say goodbye, I never thought I’d survive that monster,” he wrote on Instagram, in notes accompanying the video.

“Lost so much blood, and my leg — I don’t know if they’re going to cut it all off or if it’s going to be left in half but it doesn’t matter now.

“You are my heroes, you give me strength to carry on with your texts and calls, my only dream is to see you again. Sorry if I can’t reply to you but I’m very tired and my head hurts.”

Of Tommaso he posted: “I owe you my life.

“(Tommaso called me an idiot because I didn’t have Medicare which is Australian insurance, luckily I had another one in Italy before leaving).”