Meet the British daredevil swimming over 1,000 miles around Iceland's entire coastline: MailOnline joins Ross Edgley on a swim in the Scottish sea to find out just what it takes to face one of the most extreme environments on Earth

A rainy day in early March might not seem like an ideal time for a dip in the freezing Scottish sea.

But British daredevil Ross Edgley is not your average swimmer, having become the first and only man to swim around Great Britain in 2018.

Now, Ross has his sights set on an even more ludicrous challenge: to swim over 1,000 miles around the coast of Iceland.

Starting on May 16, Ross will swim the equivalent of the English Channel every single day in waters which can drop below freezing.

MailOnline's Science and Technology Reporter, Wiliam Hunter, joined him on a training swim to see just what it takes to prepare your body and mind to face one of the most extreme environments on Earth.

Even in training, Ross swims for up to 12 hours at a time, and consumes over 10,000 calories every day.

This puts an enormous strain on his body, that even elite athletes should find impossible to bear.

However, as sports scientists and nutritionists have discovered, if any human being could survive the challenge, it is probably Ross.

Ross' list of achievements in the world of ultra-endurance swimming already makes for staggering reading.

He holds the record for the longest continuous river swim, travelling 317 miles (510 km) in the Yukon River without stopping and is the only person to ever survive continuously swimming in Loch Ness for over 52 hours.

Yet compared to Ross' next target, those earlier feats of endurance almost seem reasonable.

As Ross casually puts it, the idea is deceptively simple: 'We leave Reykjavik in a clockwise direction, and we just don't stop until we see Reykjavik again.'

The challenge, sponsored by the BMW iX, is to swim around the entirety of the Icelandic coastline in waters that can drop below 0°C (32°F).

For comparison, it typically takes about 10 to 14 days just to drive the highway which surrounds the island.

While the distance is staggering, Iceland's geography means that swimming may actually be the least of Ross' problems.

Although he will have a support boat in tow, Ross will be entirely at the mercy of Iceland's extreme weather.

'You get 100-foot waves, 100 miles per hour winds, and they get storms of sand, ash and snow,' Ross gleefully explained.

'That's why they call it the land of ice and fire; it's kind of nuts.'

But the extreme weather and freezing temperatures won't be the only problems to overcome.

Due to his near-constant exposure to saltwater, Ross will quickly develop a disgusting condition called 'salt tongue' in which the tongue dries out so much it can start to break apart.

During his GB swim, the condition became so bad that Ross would find chunks of his tongue lying on the pillow when he woke up in the morning.

And, on the subject of sleeping, Ross will have to give up any chance of a good night's rest if he wants to make any progress.

Ross says: 'Obviously I have to swim with the tides. When the tides are with you, you swim for six hours. Tide changes, you stop and sleep.

'It doesn't matter if it's two in the morning or two in the afternoon, you get up and swim when the tide is with you.'

I met Ross on a remote beach near Ullapool, a village perched above the North Atlantic where he has been training for months.

With the waters at a Baltic 7°C (44°F), even with a thick wetsuit, gloves, and hood diving into the water feels like being slapped.

However, if Ross can even feel the cold, you would never know from his sunny demeanour.

Laughing happily, moving through the water like a shark, and somehow finding the time to coach me on my technique, he makes this look ridiculously easy.

As I bob like an iceberg, Ross explains that his preparations are only just beginning to ramp up.

In order to prepare himself for the trial ahead, Ross will build up to swimming 12 hours every single day until that becomes 'normal'.

In comparison, our half-hour splash about in the sea is barely a warm-up.

And when I finally clamber out of the water half-frozen, Ross rushes back in to pack in a few more minutes of training.

This relentless training schedule might seem excessive, but swimming around a nation requires a radically different approach.

'This isn't a race, it's a migration,' says Ross.

'Right now, I'm still a land-dwelling mammal whereas soon I'll become more sea-dwelling, and it will start to feel weird to be on land.'

Taking inspiration from Iceland's orcas, Ross says the goal is to turn himself into something more like a 'chubby migrating whale' than a 'lean dolphin'.

'I'm just trying to get fatter and fitter, it sounds like an oxymoron but that's what it is,' Ross jokes.

If he starts to lose weight during the challenge and his layer of insulating fat becomes thinner, waters as cold as Iceland's could become seriously dangerous.

That means eating is as much a part of his training schedule as swimming.

'I like to tell people that it's just an eating competition with a bit of swimming thrown in,' Ross explained as we warmed up over lunch.

'The human limit of digestion is about 120 grams of carbs every hour on the hour.

'That's like eating a very large portion of chips every hour and I just have to repeat that for 12 hours - it's simple in theory.'

In order to hit that absurd target, one of Ross' favourite pre-swim snacks is what he calls a 'pizza baguette'.

This, as the name suggests, is a foot-long filled baguette wrapped in an entire pizza.

However, having now spent a few months training in Scotland, he also says that he has become partial to three or four deep-fried Mars Bars before getting in the water.

Even with the best training in the world, swimming around an entire country is simply not something most human beings could survive.

However, it turns out that Ross may be uniquely suited to extreme swimming down to the genetic level.

During tests with nutritionists, Ross has shown that he is able to exceed the 'limits of human digestion' and eat far more than 120 grams of carbs per hour while training.

Even his body itself seems bizarrely well adapted to doing this one very specific thing.

While filming a previous documentary, Ross underwent an MRI and doctors found that his bones showed behaviour which was usually seen in 'people with cancer or newborn babies'.

In the MRI Ross' bone marrow was glowing brightly with hyperactive red marrow.

Dr Zane Shefif, the radiologist who conducted the scans, says: 'Essentially when born our bones are filled with red marrow which converts to yellow marrow, a process which is complete usually by age 25.

'The red marrow is the complex haematopoietic marrow that gives our body all the cells we need for adulthood.'

These scans revealed that Ross had a 'unique form of red marrow reconversion' which allowed him to heal faster than a normal human.

Since his bone marrow is so active, his muscles repair themselves faster and his body has a far greater capacity to withstand damage.

That doesn't mean Ross doesn't get tired or feel pain, but it does mean he can bounce back from punishment in record time.

Ross says: 'I don't want to make out that I'm impervious, I 100 per cent still feel exhaustion.

'But you know I'll do a six-hour swim with jellyfish hanging off my face in the freezing cold, then have a nap and go back to it.

'I think that everybody has a superpower; mine is just to eat and suffer.'