Prince Harry spent the night in a giant freezer to simulate the gruelling conditions he will face when he treks to the South Pole this winter.
The 29-year-old, will race with a team of injured British servicemen and women against United States and Commonwealth groups, was subjected to ambient temperatures of -35C, with wind speeds of 45mph.
Harry joked that it was a cold night's sleep. When asked what was the worst part, he said: "Going in."
ITV News Royal Correspondent Tim Ewart reports:
Harry, who is patron of the Walking With The Wounded charity spent around 20 hours in the cold chamber alongside his four teammates - all of whom have amputated limbs after sustaining injuries in Afghanistan.
Harry practised with the clothing he will wear on the 200-mile expedition, practised making and breaking camp, skiing and learned how to avoid frost-nip and frost-bite in the inhospitable climate in Antarctica.
Harry shared a tent with Captain Ibrar Ali, 36, who lost his right arm in a roadside bomb blast in 2007, and Major Kate Philp, who chose to have her left leg amputated after her Warrior armoured vehicle struck an IED (improvised explosive device) in Musa Qala in Helmand Province in 2008.
– Major Kate Philp
He knows what he's doing. He's got his military training, and it's very, very easy, so he's a good extra pair of hands.
It's great having Harry along, and hopefully he appreciates it too.
It's a chance not just for him to experience all the practical stuff that we've just done as well, but for us to get together as a team and start to get to know each other better.
It seemed very easy from the beginning, but it's certainly even more comfortable the more time we spend together.