“Hunter Killer,” a post-Cold War submarine and SEAL commando action thriller coming out Oct. 26, dives deep with Pearl Harbor’s “silent service” submariner community.

Scottish actor Gerard Butler (“Olympus Has Fallen,” “300”) plays Capt. Joe Glass, an American submarine captain on a hunt in the Arctic for a U.S. sub in distress when he also discovers that a secret Russian coup is in play.

“With crew and country on the line, Capt. Glass must now assemble an elite group of Navy SEALs to rescue the kidnapped Russian president and sneak through enemy waters to stop (World War III),” the film’s website states.

At an unusual Pentagon press conference on Monday — showing the movie’s close ties with the U.S. Navy — Butler fielded questions with Vice Adm. Fritz Roegge, the former commander of the U.S. Pacific Fleet submarine force at Pearl Harbor.

Butler noted how he went out for three days on the Los Angeles-class submarine USS Houston out of Pearl Harbor on a familiarization cruise, getting an eyeful on life beneath the waves.

The movie features the USS Arkansas, a newer Virginia-class attack submarine not yet built, but Pearl Harbor’s USS Texas is the body double in the film, the Navy said.

About 17 subs, including six of the Virginia class, are homeported in Pearl Harbor.

Butler told the Pentagon press corps “Hunter Killer” was “a chance to bring the submarine genre into the 21st century (along with) the submarine culture, and go into these new style of subs and go down and really see how these people think, work, their courage, their intelligence.”

He was given access to many of the unclassified functions on the Houston — which has since been decommissioned — an experience he likened to being in “another world.”

“I felt like I could spend a year just in sonar trying to pick up what it is they do,” Butler said. The three days spent under water gave him a greater appreciation “for what these people do every day, unsung and unseen.”

When on a submarine, “you realize the dangers, because you are there and you are 1,000 feet under water, and you go, ‘OK, what are the different ways things can go wrong,’” Butler said.

During a deep dive, Butler realized he and others were leaning backward in relation to the interior of the submarine, and the idea was born that perhaps filmmakers could put the submarine set on a giant gimbal.

“So we ended up with a 15-, 17-ton set with 40 actors and crew and all the camera equipment basically working on this hydraulic platform,” he said. The Navy said the set was in Bulgaria.

During action sequences with torpedoes underway or avoiding depth charges, “the sub could move, and we didn’t have to do the Star Trek thing,” Butler said to laughs while pretending to be jostled.

Cmdr. Corey Barker, a spokesman for the Pacific Fleet submarine force, said Butler went out on the Houston about a year and a half ago.

“All of the exterior that you see of the submarine on the surface — the actual footage, not the (computer generated) stuff — was USS Texas” shot off the coast of Oahu, Barker said.

Damage control scenes were also filmed on the USS Texas and in a trainer on Ford Island, in some cases using sailors from the submarine, he said.

Butler said the film is largely about submariners.

“So you can have fun with the gadgetry and the weapons systems and the platforms,” he said. “But at the end of the day it’s about the people operating them and how they have to think creatively and innovatively and courageously and how they have to kind of hold onto that bedrock of steadiness and honor in the most incredibly tense, dangerous situations.”