An army sharpshooter who lost both legs and several fingers when he was blown up in Afghanistan has described how he went from near-despair to sheer elation after successfully rowing across the Atlantic.

Cayle Royce was severely injured when he was struck by an improvised explosive device (IED) less than a month into his first tour of duty, in Helmand province in 2012.

The 27-year-old was "clinically dead" and had to be in an induced coma for 48 days while medics attempted to save his life.

Royce said he believed the extent of his injuries had been a hallucination, and was unaware for four days that he had lost both legs.

"I got phantom feelings - I could feel my toes, even though they weren't there. It made me think I had imagined or hallucinated my legs being blown off," he said.

"It was only when I had my bed tilted up a little after four days that I realised they weren't there. That was a low point. You realise then that you're not going to serve in the same capacity."

Read: 'Get some wheels,' Prince Philip tells a double amputee

The Row2Recovery Team, made up of four British soldiers, (left - right) Cayle Royce, James Kayall, Scott Blaney and Mark Jenkins. Credit: PA Wire

After overcoming the trauma, the 27-year-old had to undergo extensive surgery before starting rehabilitation.

The Dartmouth resident said it was a huge confidence boost to be invited onto the Row2Recovery team to help raise vital funds for Help for Heroes.

"I had always been keen on sport but after the blast I thought that side of my life had gone - it was over," he said.

The injured soldier met the Queen in November 2013. Credit: PA Wire

"I was super keen on taking part in the Talisker Whiskey Atlantic Challenge but I didn't think anyone would want me on their team, that I would be too much of a liability.

"So when the team came forward and said they wanted me, that was a huge confidence boost. It felt like I had a purpose."

Royce joined fellow amputee Corporal Scott Blaney as well as able-bodied competitors Captain Mark Jenkins and Captain James Kayll on the team.

The four soldiers celebrated after rowing across the Atlantic Ocean. Credit: PA Wire

It took the team just over 48 days to complete the 3,000 mile race - almost the same length of time he spent in a coma in the blast.

The four would work in two-hour shifts, with two rowing at the same time whilst battling against the poor conditions.

Both injured army personnel were forced to leave their prosthetic limbs in England, due to the corrosive nature of salt water.

The Dartmouth resident said it was a huge confidence boost to be invited onto the Row2Recovery team.

Hundreds of people lined Antigua's English Harbour yesterday to cheer the team on as they crossed the finish line.

Royce admitted he experienced mixed emotions as he crossed the finish line.

"The reception in the harbour was just incredible, we never expected such a turnout. I think there was a sense of immense relief.

"On Row2Recovery, I used to really enjoy the evening meals on deck where we would sit around sharing war stories, laughing and joking. To have had that again, when I thought it would not happen, was fantastic.

"In that respect, it was disappointing that it was coming to an end when we reached Antigua."

And Royce already has set his sights on his next challenge - flying a microlight over Kenya in November.