Dall sheep rams at Polychrome Pass, Denali National Park, Alaska, USA

Chilling in Alaska. Denali National Park, Alaska, USA

Someone ought to tell these Dall sheep they don't blend in here at Polychrome Pass. Their white coats may be great camouflage against the snow here in the US state of Alaska, but the warm tones of this tundra make them stick out a bit. And they aren't the only thing sticking out in this national park: It's home to the tallest mountain in North America.

Denali National Park and Preserve encompasses not only its namesake peak but more than six million acres of parkland like Polychrome Pass. And this massive park is part of something even bigger: The US federal Alaska National Interest Lands Conservation Act, established on 2 December, 1980, protected almost 250,000 square miles of wilderness all over Alaska.