Finding a lesbian role model can be difficult, particularly if she spends her life up to 300 meters (1,000ft) below the waves.

Meet Emma Boswell – the fourth woman ever to be allowed to serve on Britain’s nuclear powered submarine fleet.

Her 14-year long career with the Royal Navy started within weeks of it finally decriminalizing homosexuality.

In that time, she’s traveled to every corner of the earth and now she is plunging to the depths of the ocean for the first time.

As a medic and nuclear physicist in one she will be tasked with keeping her crew healthy so they can do their vital work.

The Royal Navy operates submarines carrying just conventional weapons as well as ones carrying ballistic missiles with nuclear warheads – but all of them are powered by nuclear reactors.

She told us: ‘They are inherently safe and my job is to make sure everything is ok. I will be looking at radioactive waste but particularly everyone wears monitors for radioactivity and I’m checking all that.’

We spoke to her as she was just about to join her submarine for her first tour.

‘I have spent 18 months in a master’s program to become a fully trained health physicist so I am a bit of a nuclear science freak now. Going to sea on Monday is the culmination of all that training and now I’m going to put it into practice.’

Until that moment, she had only been on submarines moored by the dockside. Now she’s living and working on board. And Royal Navy submarines can circumnavigate the Earth before they have to pull into port.

‘The environment is unique. You need to know a little bit about everybody’s job so if something goes wrong you can step in. It is a massive challenge.’

Despite this, Boswell wasn’t dreading the cramped environment.

‘It is small but I am going to be distracted with work. When I am not working I’m going to be sleeping so it is just getting into a routine and not really thinking about what’s going on outside and how deep you are. The guys who do it are just used to it.’

In 2011 the ban was lifted preventing women from serving on board submarines, and the first three female submariners qualified in May of this year.

‘It is male dominated. I have been to a lot of meetings where I have been the only woman sitting there. I can’t have the normal girly conversations – well, I can actually [laughs], I’m testing the guys out on that.

‘But it is difficult for them to adapt too.’

As well as being a role model for women in the navy, Boswell was one of the first open lesbians in the British Armed Forces.

She said: ‘I came out in basic training. I had one instructor who was a military policeman and he said they had just decriminalized homosexuality in the forces “but in my opinion it is wrong”. Everyone else knew and they were all men and he said to me, “for example, if you knew there was a lesbian in your mess, how would you feel?” and I said “I would probably ask for their phone number”.

‘He went bright red, the class laughed, he looked like a prejudiced idiot and I suspect he never said anything like that again. After that I’ve never really had any issues.’

Her first tour at sea took her to Key West in Florida, where she ‘instantly fell in love with the navy’. Since then she has traveled the world on duty and representing the Royal Navy as it’s cricket captain and a squash and hockey player.

But one of her strangest moments came as her ship was on patrol in the Caribbean, busting drug-runners between South America and the US. Her job was to run the on-board medical center.

‘We send out patrol helicopters to spot them and then turn the ship around to intercept. By the time the helicopter sees them, it’s all over.

‘These particular pirates knew that so decided to sink their vessel so there was no trace of what they were carrying and jump in the water.

‘One of them had hurt himself and he came in for treatment and he was pulling thousands of dollars coming out of his pockets. I couldn’t lie him on the couch to examine him because he was literally covered in money. In the end I had to call the Royal Navy Police we have on board to secure it all.

‘That’s what navy life is like, you never know what the day will bring.’

Boswell is simply unfazed by pirates, by being on the frontline, by being a lesbian in a man’s world… The only thing that scares her is the thought that one day she may have to leave the job she loves.

‘I’m coming to the end of my career. It’s terrifying,’ she confessed. ‘You sign up for a certain amount of time. I may be able to extend it but I have to be selected for that so I can’t guarantee it.

‘Thinking of leaving the Navy is exciting in some ways because then I can have a life and settle down. But at the same time, it scares the hell out of me because it’s what I’ve known for 14 years. You have a built-in social life, you have security, your bed, your food, everything you need – then in a few years time I might have to do it myself.’

You can find out about careers in the Royal Navy here.