A Queensland teenager who acted on a foolish boast to swim in a croc-infested river seems to have learnt his lesson, vowing he won't try the dangerous stunt again.

Lee De Paauw has undergone surgery for gruesome wounds to his arm after he leapt into the Johnstone River at Innisfail just before 2.30am on Sunday.

Asked on Sydney radio if he would jump into the river again, the teenager told by Nova FM's Fitzy and Wippa: "No, I wouldn't.

"I've been in that river before, you know? And I didn't expect it to happen."