An Australian teenager was nearly mauled to death over the weekend after he jumped into a crocodile-infested river, reportedly for a "dare."

Lee De Paauw, 18, was attacked by one of the predators after entering the Johnstone River in north Queensland at around 2.30am on Saturday night.

He is said to have tried to fight off the crocodile by punching it in the head, sustaining severe hand and arm injuries in the process.

Neil Noble, a local paramedic, said the teenager was rescued by his friends before being rushed to Cairns hospital.

"Reports from the scene are he was dared to jump into the water, which he did and unfortunately that area is well known for its crocodile population," Mr Noble told local news website 9News.