"All that time on your own, just sat there thinking what's going to happen. It's daunting."
For Recruit Ben Davies, the gruelling five-and-a-half hour train journey from the Midlands to Devon was the most nerve-wracking part of the recruitment process to join the Royal Marines. Nothing can truly prepare you for what's in store and it's that fear of the unknown that plays on your mind in such a confined space.
Preparation and information is key. Becoming a Marine requires a certain 'State of Mind' and even before signing up to the programme, it's vital that potential recruits acknowledge exactly what they're getting themselves into and assess whether they're up for the challenge.
Being pushed to the limit every day isn't for everyone, but through extensive research and spending time in the gym, Recruit Davies knew he'd made the right decision to apply and was ready for the Potential Royal Marines Course (PRMC).
"I was getting up at 4am in the morning, every morning, to go to the gym before work at 6am," he said. "It was more bodybuilding and weightlifting, but when I realised how important the cardio aspect of joining the Royal Marines was it completely flipped my training on its head.
"I watched as many videos, read as many articles and asked as many people as I could about the PRMC and how it worked. My Dad's an ex-Physical Training Instructor (PTI), so he gave me tips on how to improve my cardio. Everything fell into place."
Before tackling the PRMC, potential recruits are put through the Pre-Joining Fitness Test (PJFT), where they must complete two 2.4km runs on a treadmill set to 2% incline - the first in under 12 minutes and 30 seconds and the second, after a one-minute breather, in under 10 minutes.
Pass the PJFT and it's on to the PRMC, where WO2 James Smith - a PTI at Lympstone - looks for potential recruits to demonstrate a base level of fitness and mental determination.
"We want to test everything," said WO2 Smith. "Initially, there has to be a base level of fitness, a degree of mental determination and strength of mind. Guys turn up on the first morning and before it even starts they put their hand up and say, 'This isn't for me.' That straight away shows they're not right for the job.
"There's not a certain size or shape we're looking for - it's about ability and strength of mind. You'll see guys that are a bit overweight and still do very well on the course. Some of the guys are really shredded, so when it comes to being resilient and getting cold and wet, that's no good."
After a tour of the Commando Training Centre Royal Marines (CTCRM) on day one and a series of interactive lectures on day two, the PRMC begins with potential recruits being put through four gym tests: VO2 Max (the 'bleep test'), press ups, sit ups and overhand grasp pull ups.
Each gym test has a minimum requirement and a chance to earn maximum points, such as overhand grasp pull ups, where potential recruits must complete at least three and strive towards 16. A swimming assessment then follows, jumping from a three-metre diving board, completing two 100m lengths of breaststroke without pause and collecting a rubber brick from the bottom of the deep end.
It's during the Royal Marines Fitness Assessment (RMFA) where the camaraderie and competitive nature associated with being a Royal Marine initially starts to kick in, as Scott Briggs quickly discovered.
Scott, 25, claims he was "incredibly motivated" heading into the PRMC but didn't anticipate receiving so much mental support from a group of people he barely knew.
"The camaraderie that developed within hours of being together was incredible," he explained. "I think to even get to the PRMC stage you have to be a certain type of person and then being in a room full of those types of people was amazing because everyone got on and everyone just wanted to be there.
"We were speaking about what scores we got afterwards. We all wanted to beat each other. It motivates me to be even better. Being in a group of lads, you're constantly helping each other out with your different training strategies."
Day two finishes with an interview with the course Corporal, where potential recruits must show a broad understanding of the Corps and the values required to be part of it.
"The Corporal asks what your interests are, if you work well with others and about your fitness," added Recruit Davies. "It's not necessarily him getting to know you or sizing you up, it's deciding whether you're fit for the job. Working well with others is a major part of the Corps because it's like a big family. It's what your values are."
On day three, however, the physical and mental resilience of potential recruits is really put to the test, starting with the Tarzan Assault Course - climbing ladders and scaling 30-foot high obstacles - followed by a run through the dreaded bottom field assault course.
Various determination tests are used on bottom field to encourage motivation and mental strength, which WO2 Smith believes is the hardest part of the PRMC: "Everything else is an assessment to see how fit you are, but the determination test, it doesn't matter how fit you are, you're going to find that hard one way or another."
A core value of the Royal Marines is 'brotherhood' and Scott, having passed the PRMC, insists it played a major part in battling through the determination tests alongside his peers.
"When I was on bottom field, there was one incident where I thought, 'Wow this is tough,' and I just looked around me and everyone looked the same," he added. "You can take motivation from that, because no matter how hard it is, everyone around you just keeps pushing themselves. You see all the marketing material about working together, brotherhood and being part of the best club in the world - that was it."
Also on day three is the Endurance Course. The potential recruits tackle 2.5 miles of cross-country ground, tunnels and water obstacles in Woodbury Common, one of which is a submerged tunnel called 'Sheep Dip', while completing further determination tests at 'Peter's Pool' in potentially cold and wet conditions.
"On the Endurance Course, usually you just wade through it waist deep, but on your PRMC they make you do a small confidence test," said Recruit Davies, who completed his PRMC in January 2017. "You hold the rope and hold your breath for five seconds with your group. If anyone comes up before the time you have to do it again. The water was freezing, so it was a cold shock.
"Because there were a lot of lads on the course, the PTI took us to each obstacle and made us do extra exercises before and afterwards. So while some of the lads were in the tunnels, we were doing ten squats, ten push ups and ten burpees before eventually going through. When you get out the other side of the tunnels you do the same thing again and then run to the next obstacle."
And come day four on the Friday morning, it's all over. The potential recruits are given an important physical lecture with the PRMC PTI and a medical and pay brief before handing back their equipment and finding out if they've passed.
For some it could be three to six months before starting recruit training, though, which is why they're given a booklet filled with training programmes that must be populated while they wait to become a Royal Marine.
"At the end of the course we need to make sure they keep training," explained WO2 Smith. "The main reason is they need to keep their fitness ticking over. There will be a couple of lads who need to make minor improvements, so myself or another PTI will give them a warning to make sure those improvements are made."
Passing the PRMC is no easy feat and requires a certain mindset, but ultimately it provides potential recruits with the tools they need to push themselves and realise their potential to become a Royal Marine. And for some, it's a life-changing process.
"Mentally, I'm much stronger," Scott admitted. "I arrived and within three days I was able to push myself past those physical barriers. What you're asked to do is hard and you're around men that you've got so much respect for.
"The most inspiring thing is that the people guiding you are the ones who have the Green Beret and have been through it all. They've all done the PRMC, they've all done the bottom field assessment and they've all done the Endurance Course. It’s incredible."