What life is like inside the fast-attack submarine USS Minnesota

Twenty-five metres below the waves, the crew of the USS Minnesota can no longer see anything outside.

But they can hear everything.

WATCH THE VIDEO ABOVE: 7NEWS’ exclusive deep dive into life inside a submarine.

Advanced sonar systems are able to detect whales below calling to one another, fishermen above hoping for a lucky catch and enemy ships cruising hundreds of kilometres away.

“Have you ever heard of the comic book Daredevil?” the ship’s commanding officer Jeffrey Cornielle asks us from the control room of the nuclear-powered, fast-attack submarine.

“I often say it’s like that.”

Daredevil’s superhuman sense of hearing may be fictional but those on board this warship could be considered to have a superpower of their own.

The crew of 140 have to be ready to spend months within the submarine at a time, deep in a steel world without any sunlight.

Their only communication with family and friends comes through sporadic emails to ensure the ship can maintain stealth.

“I think around the 100-day mark is my longest stretch,” Chief Petty Officer Adam Shackleton told 7NEWS.

“We really have to take care of each other down here and buying into the team aspect is kind of what makes us really good at our job.”

The Virginia-class warship and its crew are visiting Perth as part of a trip the US is calling the “first pillar of the AUKUS security pact”.

Should the deal go through, Australia will receive three of these subs from America in the next decade.

7NEWS was invited on board USS Minnesota as it cruised off WA’s coast to get a glimpse of what life is like inside.

“This is the most advanced warship in the world,” Cornielle said.

“We can answer at a moment’s notice. When my boss says ‘go’, we go.”

When he says a moment’s notice, he means it.

Some of the crew sleep next to the torpedoes. The tight confines mean every square inch of space needs to be used to its full efficiency.

Hanging above the narrow corridors are intricate mazes of wires and cables connecting the ship’s many systems.

Each room has to serve multiple purposes.

“One of our submarine traditions is you won’t put your hat on a table,” Lieutenant Mike Kern said, pointing towards one at the centre of the ship’s planning room, a space barely larger than a backyard shed.

“In the event we had a medical emergency we could use this as an operating table.”

Beds are a tight squeeze. There’s six to a room. A small drawable curtain offers a sliver of privacy.

Building a connection with fellow crewmates is key.

“My first time on board a submarine was 2015. The hatch closed and we went underway and I had no idea what to expect,” Shackleton said.

“I think any moment like that, you have that small worry but you quickly realise everyone is in it together and that kind of helps the time pass.”

Days on board the submarine are split into three strict sections. Eight hours of work. Eight hours of downtime. Eight hours of sleep. Repeat.

When not operating the systems Cornielle says are as complex as those on the International Space Station, the crew have to get creative with how they pass time.

Group movie nights are particularly popular.

Meals can also be a highlight of the day with a menu that is far more varied than the small galley suggests.

There’s taco Tuesday’s, pizza Saturdays and even surf and turf Sundays.

‘I usually try to go underway with a new challenge or hobby. For this one I’m trying to read as many books as I can,” Shackleton said.

“It’s the energy you get from the small things that matter the most. For me, getting an email from home or just something to look forward to, even just little news and sports updates will get sent to us that can really just make the difference.

“You probably wouldn’t be surprised but after a long time underway you kind of run out of things to talk about with your counterparts so just the little news and updates you can look forward to in each other’s days really helps with that.”

As 7NEWS returned to return to shore after two hours inside the submarine, there was a palpable sense of relief to be outside once again.

It also raised questions about effect months on board must have.

“You start to feel like this is just your office,’ Commander Cornielle said.

An office which just minutes later had disappeared into the deep once again.