'How long can I keep going like this? Never before have I pushed so hard for so long, and I feel closer to the limits of my endurance than ever before.'In 2001, with only his dog Seraphine for company, Jon Muir set off to cross Australia on foot, from the tidal reaches of Port Augusta in South Australia to Burketown on the Gulf of Carpentaria. It was a history-making trek, the first unsupported traverse of this beautiful but rugged continent.One of the world's most accomplished climbers and adventurers, Jon had already experienced some of the harshest conditions on the planet, from the icy slopes of Everest to uncharted corners of Antarctica. Yet nothing had prepared him for his 2500-kilometre 'Great Mission'. For 128 days, his physical and emotional resources were taxed to the utmost. Often close to despair, he was thrown back on his instinct for survival, his deep understanding of the country and his remarkable inner strength.