A teenager who was attacked by a crocodile after jumping into a river for a dare has admitted he did it to impress a British backpacker.

Australian Lee de Paauw suffered extensive injuries to his left arm and confessed he was "lucky" to get out of the saltwater crocodile-infested Johnstone River alive.

The 18-year-old was at a hostel in the northern Queensland town of Innisfail with friends when he started bragging to the group that he could swim in the river in the early hours of Sunday morning.

"It all happened very fast. Pretty much as soon as he jumped in, there was splashing and screaming," Sophie Paterson, who the teenager was trying to impress, told Queensland's The Courier Mail newspaper.

"There was blood everywhere and he just wouldn't stop screaming," said the 24-year-old from Yeovil in Somerset.

She and others had dared him to jump in, but did not think he would actually follow through on his boast.

"He was walking about the local creek saying, 'I can swim out', and so we said, 'go on then', but we didn't think he would do it," she said.

The teenager managed to punch the reptile in the head twice to free himself of its grip before he was helped out of the water.

He is now recovering from the serious wounds to his arm.

"I just wanted to show the backpacker. I got her number," he told Nova FM's Fitzy and Wippa on Monday.

"The croc grabbed my arm, dragged me back out and started rolling.

"It took me about six metres from the wharf. I hit it once on the nose, it loosened a bit.

"I got another hit in and it was right on its eye. I was lucky because it just dropped me."

Asked by Channel 9 news how he would describe his stunt, the teenager replied: "Stupidity".

He added: "Just done it for Sophie."

Paramedic Neil Noble said: "He's very fortunate that he survived this incident and was able to be rescued."

Just hours later, authorities recovered the body of a man who they believe may have been mauled to death by a crocodile in nearby waters.

The 35-year-old vanished on Saturday while spearfishing alone in waters just north of Innisfail.

The attack has renewed calls for a crocodile cull in Queensland, with the Katter's Australian Party drafting legislation to go before the state parliament to allow a controlled cull.

But, reacting to the attack on Mr De Paauw, Liberal National Party Whitsundays MP Jason Costigan insisted: "We can't legislate to protect d***heads".