Cast and crew err on the side of silly in “Journey 2: The Mysterious Island,” the amusingly childish sequel to that unlikely 2008 hit “Journey to the Center of the Earth.” They’ve rendered Jules Verne’s novel into a jokey lark, with broad, corny wisecracks, comic sidekicks and everybody riffing on the ginormous lizards, humungous spiders and the like.

For those who have forgotten the conceit, the idea here is that while most consider the stories of 19th century novelist Jules Verne works of science fiction, Vernians know otherwise.

Sean Anderson (Josh Hutcherson) certainly does. He lost his dad on an epic “Journey to the Center of the Earth.” Now, years later, living with mom (Kristin Davis) and an over-compensating stepdad, Hank (Dwayne Johnson), the rebellious teen gets a coded radio message from his grandpa. Since contractor Hank used to be a Navy code breaker, they quickly realize the message is Verne’s “Mysterious Island” is real.

And they know where it is. That sets the stage for a stepfather/son bonding trip to the South Pacific, where they hire a low-rent chopper pilot (Luis Guzman, funny) and his daughter, given a teen va-va-voom turn by Vanessa Hudgens, to take them there.

They find the place, all right. Along with grandpa (played by Michael Caine), a grizzled joker stranded in the jungle.

The script makes gramps and Hank comic foils. There are gigantic bees, and poodle-sized elephants, a boiling volcano, but not – one must say – much menace. We never fear for anybody, and the action scenes are little more than 3-D showcases ripped off from the “Star Wars” movies. Director Brad Peyton plays around with slow-motion, which is what passes for style here.

It’s not Vernian or groundbreaking or smart or even that clever. This “Journey” is an action comedy for pre-teens, squeaky clean and scare-free. There’s not much here for grownups. But Johnson, the actor formerly known as wrestler “The Rock,” makes a perfectly appropriate, perfectly adorable (he plays with his pecs, and even sings a ukulele ditty) babysitter.