Identical twins are trekking across Greenland wearing different outfits for an experiment about how cold conditions affect the body.
Hugo and Ross Turner from Devon are making the journey together but will have very different experiences...
Hugo has the luxury of wearing modern protective clothing.
But brother Ross is wear the type of outfit used by polar explorer Sir Ernest Shackleton 100 years ago and will eat the type of food he had then too.
They are raising money for Spinal Research but are also being monitored by scientists from King's College London.
As they are twins they are as similar as two people can be - so this helps scientists test how different clothing and food affect the body in the same extreme Greenland conditions.
Watch Ricky's report to see how they prepared for their expedition...