Deep water is scary, even if you can swim, the unsettling presence of 'something' under the water if terrifying, whether that's a submarine, jellyfish or a bloody big whale. Now just try and imagine you're out at sea, suddenly a siren wails, the lights go out, the ship shudders and you feel the icey chill of sea water begin to snap at your feet.

The HMS Havoc simulates the conditions of a real sinking ship, with fake hull damage making way for the gallons of water which are pumped in. The sound is overwhelming, as is the speed at which the water floods in - 350 tons per hour. Within minutes, it's splashing above waist height and any equipment you drop is lost for good.

FHM went through the exercise with some cadets who unlike FHM, took control of the situation and planned a way through the chaos. For the duration of the exercise we stuck with the tactic of following orders and trying not to drown. FHM was decked out in a lovely canary-yellow high-visibility jacket too, just so the officers controlling the Havoc could make things extra hard for me, well that's our theory anyway.

FHM did their best 'men at work pose' to try and fit in.

As easy as it may look on the video, trying to hammer the wedges into the hole whilst water pours out is almost impossible, especially when that water is spraying in to your face. We can only imagine how much harder it would be if it was salt water. As time went on our body temperature plummeted, making it difficult to distinguish between the wooden wedges we were hammering and our thumbs. 

We were all shown how to deal with the breaches on the floor first, which seemed quite simple when the room was dry and not full of water. When it was flooded it was impossible, half the equipment floated away or was just too hard to spot in the dark.

After the first round, we took on a different room which had a jet of water so pressurised it could strip skin from your hand. FHM made a mental note to avoid that and ploughed in to attaching a wall cushion and supporting struts to stop the water. By the end of the exercise the room was almost filled to the roof, so we had to swim out whilst following the sides of the room to avoid the skin stripping jet of water.

Eventually we were struggling to keep our footing whilst blocking the holes. That water is over 5 ft deep.

Overall it was a hectic experience and made the prospect of being aboard a sinking ship seem even more horrendous. It definitely tests your mettle and not a lot of people can stand up to the task. The drill instructor explained that a group of rugby lads who came in collapsed under the pressure, with one clinging on to a pipe in the corner and begging to leave. Then again,  a small woman - possibly a librarian - came in and took over the situation, barked orders and rose to the challenge.

It takes all kinds of people to work in the Royal Navy, FHM has learned that they certainly couldn't manage it, but the real question is, could you?

To find out more about the Royal Navy's work check out their official website.

Thanks to Sean Clee for recording and editing the video,David Sherfield for the images and everyone at HMS Raleigh for being such good sports.