Giant prehistoric shark movies are supposed to be cheesy, right?

There’s no other logical reason why the actors in “Meg 2: The Trench” chew everything they can — scenery, clunky dialogue — like the film’s hungry sea creatures chomp on tourists. Even star Jason Statham, as the stone-faced survivor of the first megashark movie, attempts to imitate a pufferfish before wading into water 25,000 feet below the surface. There’s a crack about his deviated septum.

Hilarious stuff, we’re to believe. Or are we?

The sequel starts out halfway serious. Statham’s Jonas Taylor battles ocean polluters with the help of his other surviving pal, Cliff Curtis’ Mac Macreides, while playing concerned surrogate father to Meiying (Sophia Cai), the supersmart, adventurous 14-year-old daughter of a character who didn’t live to see the second movie. Her ultrarich, ecologically conscious uncle, Jiuming Zhang (Wu Jing, the charismatic star of Chinese megahits such as the “Wolf Warrior” movies), has developed colorful submersibles and Iron Man-like exoskeleton suits to explore the Pacific trench where the megalodons have hung out since before the dinosaurs came and went.

Zhang has also raised a meg he’s named Haiqi at his incredibly ritzy research facility. The place is one of several Bond villain lair-like installations that production designer Chris Lowe, a veteran 007 film art director, almost convinces us could exist. Zhang thinks he’s buddies with Haiqi, until she busts out and heads to the trench for mating season. That just so happens to coincide with the deep dive to the same area by Jonas, Zhang, a stowaway Meiying and some expendable researchers.

But the megs, who include a beat-up big daddy larger than any seen before, are hardly the only threat down there. There are smaller, faster amphibians with longer teeth. Also, a rogue rare earth metals mining operation run by psychopaths. Not to mention the biggest, angriest octopus seen on screen since Ray Harryhausen’s stop-motion tentacles wrecked San Francisco in 1955’s “It Came From Beneath the Sea.”

Speaking of under the sea, the terrifying trench floor is beautifully rendered, lit by fire-hued volcanic vents and bioluminescent kelp forest fauna. Despite its title, though, we only spend about a quarter of the film in that wet wonderland. The big, climactic action takes place at a tacky Thai beach resort, where the prehistoric and human monsters converge for confrontations so increasingly ridiculous you’ll be laughing at them as much as at lines like “That was close. Too close!”

But will you laughwiththem? In this summer when one over-the-top and over-the-hill action sequel after another has fallen flat with audiences, perhaps we’re ready for one that invites us to snicker.

Though “Meg 2” is by far the biggest production he’s ever helmed, director Ben Wheatley doesn’t appear to be in over his head with this; special effects and stunts are proficiently delivered, no matter how ludicrous. A darling of the English indie genre scene back in the day, Wheatley was no slouch at finding smart humor in such dark, violent entries as “Sightseers,” “Free Fire” and “Kill List.”

Whether what makes for laughs here is intentional or not, smart humor and “Meg 2” do not exist in the same universe. Unconvincing brainiacs shouting “thermocline breach!” just sound extra dumb. Perhaps Page Kennedy, back as Jonas’ ally DJ, has the right idea. He just powers through the bad quips he’s given with all the sass he can muster. You’ll chuckle every time, provided you can get on the whole show’s wavelength.

Bob Strauss is a freelance writer.