It's the most extreme cold weather environment in the world - and Royal Marines have been busy teaching their American counterparts exactly how to survive in it.
Cold weather warfare specialists from the Royal Marines put more than 200 men and women from the United States Marine Corps through their paces in Porsangmoen, Norway, this month.
They have learned how to fight and survive in one of the harshest environments on the planet - some 300 miles inside the Arctic Circle, in some of the most tactically challenging and physical arduous conditions.
As part of the training, the students are exposed to some of the unique threats of the frozen environment - including practising how to escape from a hole in the ice of a frozen lake, avalanche safety procedures and how to fight on skis.
Sergeant Simon Bramley, 30 Commando's Unit Mountain Leader, said: "We're here training the United States Marine Corps and we've been given that task because we are the subject matter experts in this environment.
"We've been coming here for over forty years and we've developed a capability which allows us to operate effectively in this environment.
"By the end of this training, the United States Marines will know that if they can operate in this environment, they'll be able to operate in any environment."
The course takes place over three weeks, during which the Marines are taught to fight, survive and move while enduring temperatures as low as -30C.
Porsangmoen is the world's northernmost military garrison, and the associated Halkvarre training area is the largest in Norway.
It provides superb conditions for troops to train and hone their skills in the most unforgiving of environments.
Meanwhile, the jungle warfare specialists of 40 Commando have been applying the same extreme environment test in another part of the world.
Taunton-based Delta Company are putting all of their soldiering skills to the test in the jungle of Belize - another hostile region where the heat, wildlife and lack of food can all pose a danger.
