An infantry platoon marches across the barren landscape. Says the captain, "We will march 25 miles today, soldiers!" And indeed, by nightfall, they have marched 25 miles. But when they prepare to set up their sleeping quarters, they find that they are in exactly the same place they started! They marched in an exactly straight line, and no other transportation was used.
It is necessary for the soldiers to wear special clothing to survive here, and there is a specific place I am talking about
Another hint: (Don't read unless necessary)
The distance of 25mi matters