Few stories of adventure and survival against the odds capture the imagination more easily than the remarkable tales of exploration to the wastes of Antarctica. Names such as Shackleton and Scott are still familiar, a century after their journeys in icy waters - the equivalent then to, today, taking a rocket to Jupiter.

And the full saga of the men who mapped the Antarctic is impossible to relate without applauding the unique contribution of Irishman, Tom Crean.

Crean, a Kerryman, was an unsung hero of polar exploration and yet his inspiring and quite remarkable story has remained largely untold for the best part of a century.

He was a poorly-educated farmer's son from the Dingle Peninsula who rose from obscurity to be at the centre of the dramatic events which shaped the early history of exploration to the last untamed continent on earth.

He sailed on three of the four famous British expeditions to the Antarctic and spent more time exploring on the ice than either of the more celebrated figures, Scott and Shackleton. He was also one of the few explorers to accompany both Scott and Shackleton, who were bitter rivals.

And he outlived them both.

The story of Tom Crean is that of an ordinary man who did extraordinary things. But until now no book had been written about him and precious little information about his action-packed life can be found in the archives. This book took three years of research in Ireland, Britain, New Zealand and North America, interviews with key people such as Crean's daughters and Broke Evans, the son of a man whose life Crean saved, and sifting through 100 books, private letters, official records and an endless chain of archive material.

Crean was born in 1887 on a remote hillside farm near the village of Anascaul in Co Kerry. By coincidence, he shared a birthday with another great adventurer, Sir Edmund Hillary, conqueror of Everest. At the age of 15, Crean ran away from home and enlisted in Queen Victoria's navy and, by chance, found himself stationed in New Zealand around Christmas, 1901. Also in dock was Captain Scott's Discovery, busily taking on supplies before embarking on the first concerted attempt to explore the Antarctic continent - Terra Australis Incognita or the unknown southern land.

Shortly before Discovery's departure, a truculent sailor attacked an officer and fled, leaving Scott with a vacancy. Crean volunteered to fill the gap. He spent the next two years with Discovery, serving a polar apprenticeship which was the basic grounding for his later exploits. In 1910, when Scott was ready to launch another assault on the South Pole, he readily recruited Crean to accompany him.

On this ill-fated journey, Crean dragged a sledge 750 miles across the ice and was among the last three men to see Scott alive. He left Scott barely 150 miles from the South Pole and Crean wept openly at the disappointment of being denied a place in history. Some 10 months later, he was among the searchers who buried Scott's dead body in the ice. He wept again.

Tom Crean's return journey to basecamp ranks as probably the finest feat of individual heroism from the entire age of polar exploration, but it was inevitably eclipsed by the tragedy of Scott's doomed polar party and was to become a forgotten chapter in history.

Crean and his two colleagues - Bill Lashly and Lieut Edward Evans - faced a 750-mile trek to safety. Only

Evans could navigate and before long he succumbed to scurvy and lay dying. He ordered Crean and Lashly to leave him behind and save themselves, but they refused and dragged him on the sledge for as long as their strength would hold out.

When they could pull no further, Crean volunteered to march the final 35 miles to bring rescue. He had already walked for three and a half months, 1,500 miles. He carried no tent or sleeping bag and his only food was two sticks of chocolate and three biscuits.

He walked, stumbled and crawled for 18 hours and somehow reached help. Dog teams raced out to Evans's aid. Crean was eventually given the Albert Medal, the highest award for gallantry.

Only a few months after returning from Scott's ill-fated expedition, Crean was heading back to the Antarctic, on board Endurance with Shackleton. Theirs was to become the greatest story of survival to emerge from the entire era of polar exploration and Crean, once again, was at the centre of momentous events.

Endurance was crushed by ice in the Weddell Sea and the 28-man party was stranded for months on a drifting icefloe. After steering their lifeboats to the uninhabited Elephant Island, they decided that six men should set out in the 22-foot open boat, the James Caird, 800 miles across the violent Southern Ocean to South Georgia to bring rescue.

Crean begged Shackleton to take him on the hazardous crossing and 17 days later, when South Georgia was reached, only three of the six were still standing - Shackleton, the peerless navigator Worsley and Tom Crean.

But the men had made landfall on the "wrong" side of the island and rescue lay at a whaling station across the unexplored glaciers and peaks of South Georgia. With only light clothing, sparse food and a carpenter's axe, Shackleton, Worsley and Tom Crean made the first crossing of South Georgia and finally saved their stranded comrades on Elephant Island. It was Crean's last act as an explorer.

When he retired from the navy, he returned to Anascaul where he married, raised a family and opened a pub called the South Pole Inn, which survives to this day. His neighbours affectionately called him Tom the Pole.

But his story has since lain largely undisturbed. While Scott and Shackleton earned huge recognition for their efforts, Crean's life remained under wraps.

This was due in part to Crean's own background. Most of the characters on these early expeditions were middle-class products of English public schools, universities or officer-training colleges. Keeping detailed diaries and writing volumninous letters came easily to these people. But Tom Crean came from the other side of the ski tracks. He was barely literate and therefore left little behind. There are no diaries and only a few short and poorly-crafted letters.

Another reason for the lack of coverage lies in Irish history. When Crean returned home in 1920, Ireland was slipping towards war and any association with the British was deeply unpopular. Although Crean was no political figure, he wisely chose to keep his head down and refused to discuss his extraordinary exploits. He never gave an interview.

But the world moves on, and it is now possible to assess Crean's outstanding contribution to polar exploration more freely and give him the recognition he rightfully deserves. It also allows us to plug an important gap in the enduring history of polar exploration.

An Unsung Hero: Tom Crean - Antarctic Survivor by Michael Smith is published by The Collins Press, price £20 in UK

Michael Smith will deliver the Tom Barrington lecture in the County Library, Tralee, Co Kerry tonight at 8 p.m.