Prepare to see a grave (and aquatic) side of two-time Academy Award nominee Jude Law.

In Focus Features’ suspenseful adventure-thriller “Black Sea” — which premiered in New York on Wednesday night — Law gives a charged performance as an abruptly unemployed submarine captain who’s commissioned to lead a team of shoddy British and Russian sailors in search of a Nazi U-boat filled with gold that was lost during World War II.

For the taxing but rewarding project, Law gained weight (by eating lots of steak), shaved his head and learned to speak with a heavy Scottish-Aberdeen accent.

“This was a role that I had never done before, and it was challenging,” Law, 42, told Variety prior to the film’s screening at the Landmark Sunshine Cinema. “I was immediately fascinated by my character’s complexity. He’s a man torn between revenge and reclaiming his dignity. He wasn’t a hero, but more of an anti-hero. Everything just turned me on, the whole idea of the film and the film’s message, that greed does not win out — (greed) which is deep in all our desires.”

Directed by Oscar winner Kevin Macdonald (“One Day in September”), “Black Sea” was filmed almost entirely on a retired Soviet-era submarine located on Britain’s Medway River, as well as in a giant water tank at Pinewood Studios. Law and his 12 co-stars — including Ben Mendelsohn and “Argo” actor Scoot McNairy — spent about 11 hours a day for three weeks shooting inside the submarine.

“I had to get used to not hitting my head. When you stand up quickly, you meet with something sharp and hard,” Law disclosed, not all in jest. “We all did get a few bumps on the head. First aid was brought in because someone had opened their skull on a piece of metal.”

And while he wasn’t impeded by claustrophobia, bodily odors were certainly pungent.

“We got to know each other very well. Once you squeeze (in) 12 guys and a film crew, there’s not a lot of room to maneuver,” he said. “The longer we were in there, we started to smell of man. The smell of diesel and human sweat was not pleasant.”

But Law hardly seemed affected by the hazardous and uncomfortable environment. “Jude never complained and gave it his all,” said Macdonald, whose original story idea came about nearly six years ago, after he read of the Kursk submarine disaster of 2000, in which 118 Russian sailors and officers died. “He removed the Jude Law that we all know and love, and completely transformed himself. He’s the type of actor who is willing to become anybody you want him to be.”

That “anybody” was also melodious. After being cooped up in a confined space for hours, the cast would blow off steam by belting out songs.

“It was a lot of rowdy, rude, sea-chantey versions of ’80s pop songs, usually led by Ben Mendelsohn,” Law said with a laugh. “We were in there for weeks and sang through every song imaginable.”

On the heels of this project, Law — who also stars in the acclaimed “The Grand Budapest Hotel” and has upcoming films “Spy” and “Genius” (which is headed to the Berlin Film Festival) — will begin filming Guy Richie’s medieval-set “Knights of the Round Table: King Arthur” in March.

“I’m very, very excited to work with Guy again,” Law said of what will mark a third collaboration with his good friend. Though he’s not playing a foe. “I don’t see my character as a villain. You can’t go in and say, ‘I’m the villain’ and start twirling your mustache,” he said. “But he’s got bad elements.”

Following the “Black Sea” screening, Law convened with Macdonald, the film’s screenwriter Dennis Kelly, executive producer Jim Cochrane and composer Ilan Eshkeri at the Eurasian-themed restaurant Macao for the film’s after-party, where he sat at a corner table cracking jokes and chatting with his ample supporters.

“Black Sea,” from Focus Features, opens in theaters on January 23.

(Pictured: Jude Law and Kevin Macdonald)