Explorer Sir Ranulph Fiennes is set to take on blizzards, temperatures as low as -30 degrees Celsius and his own fear of heights as he ascends one of the world's most perilous mountains.
Despite being 72 and in ailing health, the seasoned adventurer from Exmoor is pursuing a unique record - to become the first person to climb each continent's highest mountain and cross both polar ice caps.
His gruelling expedition will this week take him to Argentina and Aconcagua, South America's highest mountain, which towers at 22,838ft (6,961m).
It will be a daring feat made all the more breathless by the low-oxygen levels he must endure, as he suffers from a respiratory condition.
Sir Ranulph's famed hunger for physical challenges has stayed strong since suffering two heart attacks and undergoing double bypass surgery in 2003.
He is now more than halfway to completing the Global Reach Challenge in aid of Marie Curie, having already crossed both polar ice caps and climbed Mount Everest in Asia, Mount Kilimanjaro in Africa, Mount Elbrus in Europe and Mount Vinson in Antarctica.
To complete the world first, he still needs to summit Aconcagua, Mount Carstensz in Australasia, and Denali, the highest peak in North America.
He is using his pursuit to raise funds for Marie Curie, and the money raised will help the charity provide care and support to people living with a terminal illness and their families in the UK.
Sir Ranulph Fiennes said:
Dr Jane Collins, chief executive of the charity, said: