It's no walk in the park, this Captain Kirk business. Beaming down from the Enterprise to 23d-century Earth - just think what that does to your molecules. Jet-packing through deepest space, with only a thin metal suit and a helmet protecting you from imploding into the nothingness - try that sometime.

But for Chris Pine, who returns as James Tiberius Kirk, the maverick skipper of Star Fleet's storied ship in the sequel to J.J. Abrams' 2009 mega-successful reboot, the toughest task on Star Trek Into Darkness was just running. And running. And running.

Like, fleeing across dense, exotic turf, with primitive tribespeople throwing deadly projectiles. And, oh, right, there's a volcano about to erupt.

"The most physically demanding?" says Pine. "It was probably just the sheer amount of running I had to do in the beginning of the film, when I'm trying to get back to the Enterprise from this red planet. Karl Urban [he plays Bones, the Enterprise's chief medical officer] and I were just running and running - it seemed like for a week and a half."

One of the rare sequels that's at least as good as its predecessor, Star Trek Into Darkness opens Wednesday. It was shot with IMAX cameras and 3-D technology, and it is probably the most visually stunning of all the Trek films - Abrams' inaugural effort, and the 10 that went before it (six with William Shatner and Leonard Nimoy as Kirk and Spock, four with Patrick Stewart and his Next Generation crew.)

In Into Darkness, Zachary Quinto dons the Vulcan ears for his second time as first officer Spock, guided by logic and a respect for Star Fleet rules. Kirk, of course, throws logic - and the rule book - out the window, which makes for a considerable amount of tension. And there's tension, too, between Spock and the Enterprise's Lieutenant Uhura (Zoë Saldana). A lovers' spat.

"This is probably a bad reference that's not going to make any sense, but there's a Goonies quality to Star Trek," says Pine, on the phone from London (where one of the darker parts of Into Darkness takes place).

The Goonies being that seminal 1985 flick in which a gang of misfit kids find themselves facing danger and spelunking for treasure. Pine, a third-generation Hollywood pro, was all of 5 when the Richard Donner-directed adventure was released.

"Here's this group of people from disparate backgrounds," he explains, working his Goonies/Trek analogy hard. "They're not all getting along, but they're faced with these tremendous challenges, tremendous odds. And it's fun to see them work through their differences, to come out the other side.

"And while in Star Trek Into Darkness there's plenty of reference to some of the awful things we unfortunately have grown accustomed to - namely, terrorism - there's also always time for a smile. There's always time for a sense of humor. There's always time for laughter.

"I appreciated that about the original Star Trek series, and I love that J.J. brought it back into ours."

Capt. Kirk isn't the only familiar franchise character Pine has tackled lately. Last year, after finishing Into Darkness, he filmed Jack Ryan, a reboot of the Tom Clancy CIA series. Alec Baldwin (The Hunt For Red October), Harrison Ford (Patriot Games, Clear and Present Danger), and Ben Affleck (The Sum of All Fears) have played Ryan before.

"Kenneth Branagh is directing," Pine reports. "Keira Knightley is in it, Kevin Costner is in it. I think our take on the franchise is a good one," he adds, comparing it to 3 Days of the Condor. "It has that kind of intelligent thriller aspect to it, and the character isn't like a Jason Bourne or James Bond. He's a man more comfortable in the background, more comfortable using his mind as a weapon - but then he gets thrown into these unbelievable situations."

Jack Ryan, in which Branagh has cast himself as the archnemesis, is down to open Christmas Day.

Aussie actress' daunting (almost) debut. Sure, Elizabeth Debicki has made movies before. One, a movie in her native Australia, set in the outback, with Olivia Newton-John in it. (For the record: it's a wedding road comedy, A Few Best Men.)

So being cast in one of the significant roles - that of Jordan Baker, the golfing flapper friend to Nick Carraway - in the $130 million, Leonardo DiCaprio-starring, Baz Luhrmann-conceived adaptation of F. Scott Fitzgerald's The Great Gatsby was not a big deal for the 22-year-old actress. Not at all.

"In a funny way, the epic scale of it all was sort of a blessing," she says. "There was so much going on that as an actor, I just learned to really focus in on my specific tasks. I put my blinders on. But certainly, at the very beginning, it was all sort of amazing to be sitting opposite these actors reading scenes, or just walking onto a set that was so beautiful and enormous. And Baz is a director who I have admired for so long. I had to pinch myself a lot."

Debicki, the daughter of classical ballet dancers who started out in Paris and moved to Melbourne when she was 5, shot an audition role for The Great Gatsby and "somehow, amazingly," it got to Luhrmann. Before she knew it, Debicki was on a plane to Los Angeles to test with Tobey Maguire, who plays Carraway.

"Nerves and terror," she says, laughing. "It was one of those situations that you don't ever expect to be in, so you just try and take in all the information - and then on top of that it's an audition. You know, you're trying to get a job. . . . I've often thought it's amazing that I can really remember any of it.

"But I think the worst part was definitely when I came home, back to Australia, and I was doing a play at the time, and I had slipped back into my normal life. The audition definitely felt like a bizarre kind of dream. I wasn't entirely certain that it happened until a month or so later, when Baz called."

For Debicki,       Jordan represents a thoroughly modern Roaring Twenties woman.  "Jordan made her own money. She was kind of nomadic. She was a new breed of woman. And I was very conscious of what she meant as a sort of symbol of the times, and a symbol of the new social life, which was liberating and very hard and fast - lots of parties and drinking and things."

And had Debicki golfed before she landed the part?

"I quite honestly do not have the patience for it," she confesses. "I understand the concept - you know, if it's a nice day and the sun's out and there's a breeze, play golf. But I would rather just sit on the grass and read a book than walk around with a bag of clubs.

"But I had lovely instructors, and they were always very, very encouraging. One of them even tried to make me give up acting to pursue a golfing career," she says, laughing again.

"No way, buddy."

Contact movie critic Steven Rea at 215-854-5629 or srea@phillynews.com, or follow on Twitter @Steven_Rea. Read his blog, "On Movies Online," at www.inquirer.com/onmovies.