Guantanamo is history.

The thought that this centerpiece in the global war on terror would soon be closed without ever having its day-to-day operations independently documented on film is what propelled National Geographic Explorer to the U.S. military enclave on Cuba’s southeast coast.

Director John Else might well have taken his time. The tropical prison, caught in the crosscurrents of politics, the courts and the absence of a solution to the disposal of some 60 remaining “hard core” terrorists, is not likely to be closed soon.

Whether it should or not has deeply divided Americans. Two years ago, with tales of beatings and suicide leaking out, seven out of 10 Americans thought prisoners should not be kept there indefinitely. But after President Obama made planning for its closure one of his first executive acts, more of us thought that he should not close it than thought he should — 45 to 35 percent — according to a Gallup Poll.

“Explorer: Inside Guantanamo,” premiering April 5, is not designed to sway viewers one way or another, much to its credit.

But if ever the shopworn Latin phrase res ipsa loquitor was applicable, it’s here: The thing speaks for itself.

From the inside, for the most part, it looks like any “supermax” federal prison, with the majority of inmates sealed up around the clock in 8-by-12 foot dorm-like rooms. The filmmakers were forbidden to talk with them and Gitmo censors blurred their faces before clearing the film. (Otherwise, they were free to edit their story however they wished, without interference.)

The Pentagon should be pleased. Viewers will not witness the “enhanced interrogation techniques,” including the sleep deprivation, extended stress positions, round-the-clock bombardment of rock music and harsh lights, sexual provocations by female interrogators, prolonged isolation and, in a very few cases, according to the CIA, the waterboarding that some prisoners endured in the notorious Camp Seven, reserved for “high value” prisoners.

That has all ended, supposedly. There is not a hooded, orange jump-suited prisoner in sight. And as the Explorer team shows, the more “compliant” prisoners have extended time to wander in the sunny yard, mingle and eat communally.

“We’ve got nothing to hide here, nothing I’m not proud to show my kids and my mom,” says Rear Adm. David Thomas, commander of Joint Task Force Guantanamo, early in the film. Thomas is in charge of enemy combatants as well as the program to extract useful intelligence from them. It’s early in the film.

“Can you show us everything here?” the interviewer asks.

“No,” Thomas responds in a non sequitur. Camp 7, which has “high value detainees,” he says, will be completely off limits because of “national security.”

When you learn that he was in the Pentagon when one of the hijacked airliners hit, lost many friends, and keeps his singed uniform from that horrific day in his closet, you don’t easily shrug off his rejection of the notion that Guantanamo has become a recruiting magnet for jihadis, which is the consensus among most military and intelligence officials.