Sailing on a U.S. nuclear attack submarine is a trip into a cramped, timeless, windowless undersea world. My team and I got an exclusive trip on the USS Missouri during exercises in the Atlantic Ocean off the coast of Florida.

The first thing we noticed is how just how precious space is on board -- and how the crews, who spend six months at sea on deployment, manage to stay out of each other's way. About a third of the 337-foot vessel is taken up by the onboard nuclear reactor and propulsion, leaving a tiny living and work space for the sailors.

The Missouri spent 163 of 181 days underwater on its last deployment.

Every last inch is conserved and made ready for multiple uses. The officers' wardroom, where senior officers dine, doubles as an operating theater in medical emergencies. The torpedo room doubles as exercise room and sometimes bunkroom. Sleeping space is in particularly short supply. In fact, Virginia-class submarines like the Missouri have fewer beds than sailors -- about 94 for the 135 crew. That requires what the crews not so affectionately call "hot-racking," where sailors share bunks and sleep in shifts.

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Night and day are indistinguishable on board. It is an endless series of eight-hour shifts. To keep a sense of sanity, the mess rotates breakfast, lunch and dinner every few days so the late shift isn't stuck eating meat and potatoes for breakfast.

Personally, I was amazed at how deftly the crew manages confinement with a smile. Submariners have developed a long list of unwritten rules to help keep the peace, particularly on long stretches underwater. Crews don't talk politics on board. They don't slam doors, knowing someone is always sleeping. And they learn to bend, duck and dodge just to avoid running into each other walking back and forth through the tight hallways.

Submarines are an all-volunteer service, a fact that brings a certain amount of pride. And submariners grant it is a certain kind of person who chooses a life under the sea. That pride is the true secret to keeping the peace. They each respect the sacrifice they're all making -- a special camaraderie built on shared sacrifice.

So how do they pass the time aboard a small enclosed vessel with 130 other sailors so close together?

"Working out," one sailor aboard the Missouri told me while also adding, "I personally spend a lot of time playing cards, or just staying away from other people I don't want to be around."

"It depends on the day," another sailor told me. "Sometimes you go find a quiet corner and read a book," or watch a movie with your buddies on the projector in the crew's mess or the cafeteria aboard the sub.

While politics is a seldom discussed topic, the sailors said the "politics" of sports, and how one's team stacks up against another, is always fair game.

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"Slamming doors" and other loud noises, multiple sailors said, because sleep is at a premium in an environment of staggered shifts aboard an enterprise operating 24 hours a day.

There is also the etiquette of shower time -- three to five minutes being what these sailors constitute as being considerate of others since it is all about the "water run time" and the cycling out of dirty water for clean water these sailors must do.

Because of their extended periods beneath the surface, submariners are also allowed certain liberties that others in the Navy are not, such as growing beards to a certain length and a less regimented directive on hair length and style.

One sailor said some aboard the Missouri have taken part in a "Mighty Mo" contest -- a play on the nickname of the Missouri -- where they see who can grow the best Mohawk.

And they make a lot of sacrifices. When they're at sea, submariners have limited contact with home. Emails come and go only when the submarine surfaces, which was for fewer than 20 days during their last six-month deployment.

And even then, communication isn't guaranteed. Any time the submarine sends a signal, it identifies its position, and loses the secrecy that is at the core of the crew's mission. There is only one washer and dryer on board, so clean clothes are a luxury. But submarines are famous for their good food, always topped off with a desert or two, including ice cream. Movies and cell phone video games are another welcome break.

But the traditional pastime is decidedly old-school: cribbage. I got drafted for a few games -- and let's just say I was not up to Navy spec.

Sleeping on board was oddly comfortable for this first-timer. The bunks are tiny; stretched out, I felt like I was in an MRI machine -- or worse, dozing off in a casket. But the hum of the boat lulled me to sleep for a solid few hours undisturbed.

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