Two Australian men flew from Sydney Monday on their way to Antarctica for an attempt at a record-breaking pole trek.

Justin Jones, 28, and James Castrission, 29, plan to walk unassisted from the Antarctic coast to the South Pole and back, an achievement that has never been accomplished. Each man will pull a sled with 160 kilograms of food and supplies.

The men, who have been friends since their school days, made history four years ago by kayaking 3,300 kilometers across the Tasman Sea to New Zealand. This time, they say they have trained in the Arctic to prepare for the cold and have each put on about 20 kilograms of body weight in expectation of heavy weight loss during the trek.

Jones told VOA in August that he and Castrission were inspired by the adventures of Britain's Robert Scott and Norway's Roald Amundsen, who engaged in a dramatic race to the South Pole 100 years ago this month. Amundsen reached the pole first, while Scott and his four colleagues died on the return trip.

Jones and Castrission boarded a flight Monday to Santiago, Chile, where they will meet a Russian cargo flight bound for the Antarctic.

Castrission's mother, Vivienne, was among those at the airport to see them off. She said she tried desperately to talk the men out of the kayaking adventure, but she is much calmer about it this time.