A flight to Antarctica is among the hardest in the world because of the freezing conditions and because a runway must be physically created on the ice.

New Zealand’s air force said on Wednesday it had evacuated three people from a United States research base in Antarctica, in what it said was a high-risk operation in freezing temperatures and perpetual darkness.

Royal New Zealand Air Force conducts high-risk mission to evacuate three individuals from McMurdo Station during 24-hour darkness and extreme cold.