The Grand Canyon is truly "Grand". It is 277 miles long, has a maximum width of 18 miles, and can be over a mile deep in certain places.
Among all the National Parks of the United States, Yellowstone is the most unique. Imagine all the wildlife and natural beauty thriving above a sleeping giant, a supervolcano.
Mauna Kea is the highest peak of this underwater mountain range. Its height measured from its underwater base to top is more than the height of Mt. Everest.