The Grand Canyon is indeed a very big hole in the ground. It is 277 miles (446 km) long, up to 18 miles (29 km) wide and more than a mile (6,000 feet / 1,800 meters) deep.It is the result of constant erosion by the Colorado River over millions of years.he Grand Canyon is in the northwest corner of Arizona, close to the borders of Utah and Nevada. Most of the Grand Canyon lies within Grand Canyon National Park and is managed by the National Park Service, the Hualapai Tribal Nation and the Havasupai Tribe.