The Royal Marines describe themselves as 'the world's most elite amphibious fighting force'.
Part of the Royal Navy, the force is trained to respond rapidly to international crisis situations.
They're also trained to be deadly.
So what sort of person actually has what it takes to become one of these super-soldiers?
To start with, every individual hoping to become a Royal Marines Commando has to undertake a gruelling 32-week 'basic training' course.
As the longest infantry training in NATO, it's fair to say that the Commando course is anything but basic.
The course ends with the infamous 30-mile 'yomp' across Dartmoor, carrying full kit weighing 32lbs.
The yomp is known for being one of the most physically challenging tests to exist in any military.
Sadly, the physical demands of the exercise caused the death of one young recruit back in 2015, which led to calls for the training to be softened.
But the force maintained that this was what was required to turn a civilian into a Royal Marines Commando.
Before they reach that point, they have to learn to live, breathe, eat and clean like a Royal Marine.
The philosophy of 'husbandry' is that if you can’t make your bed or polish your boots properly, then how can you be relied upon in combat?
During training, the Commando values of excellence, integrity, self-discipline and humility are drilled into recruits.
Along with this, trainees are taught to embody the Commando qualities of, determination, courage, unselfishness and cheerfulness in the face of adversity, and the all-important 'commando mindset': 'be the first to understand; the first to adapt and respond, and the first to overcome'.
The average Royal Marine recruit can expect to receive around 4-6 hours of sleep per night; there’s a reason that they're known as 'nods' - due to a combination of huge physical exertion and sleep deprivation, recruits will frequently 'nod off'.
It's no wonder that 40% of Royal Marine recruits drop out before the end of the 32-week training due to homesickness or "professional issues".
Many also suffer serious injuries that prevent them from finishing the course.
So why does anyone want to apply?
Forces Network's Cassidy Little decided to join the Royal Marines after being told by a friend:
"Everybody respects a failure; nobody respects a quitter. At least as a failure, you gave it your best."
He said: "It's the longest and hardest basic training in the world…their current slogan was 99.9% need not apply.
“Everybody including myself had no expectation of me succeeding.
"They literally teach you from the very basics - how to iron something, how to wash, how to make your bed, how to use a knife and fork, how to brush your teeth. If you can’t be trusted to maintain your own teeth, how can you be trusted to manage a weapons system?"
"For the first four weeks, you're not allowed to quit. They've spent so much money getting you to that point, they want you to have a good go at it before they send you home.
"Our final graduation group had 13 of the original 54 guys.
"It was tough, but it should be tough."
There's no doubt that it takes a special sort of person to become a Royal Marines Commando; as the force tells potential recruits on its website:
"There's one thing that all our people share. That special state of mind. It’s the foundation of life in the Royal Marines. To prove you have it you’ll need to demonstrate certain qualities, every day."
Let us know why you became a Royal Marine in the comments section below...