The Grand Canyon is a colorful, steep-sided gorge[?], carved by the Colorado River, in northern Arizona. The canyon, considered to be among the major natural wonders of the world, is largely contained in the Grand Canyon National Park - one of the first national parks in the United States. President Theodore Roosevelt was a major proponent of the Grand Canyon area, visiting on numerous occasions to hunt mountain lions and enjoy the breathtaking scenery.
The canyon, created by the Colorado River cutting a channel in gradually rising land over millions of years, is about 350 kilometers long, and ranges in width from 6 to 29 kilometers.
Aside from casual sightseeing from the South Rim, white water rafting[?] and hiking are especially popular. The floor of the valley is accessible by hiking, muleback, or by boat or raft from upriver. Commercially organized rafting trips, using 35-foot, 15 person "baloney boats" equipped with outboard engines, make the trip from Lee's Ferry[?] to Diamond Creek[?] in about six days. 18-foot rafts and dorys powered only with oars[?] and paddles, and take over two weeks to complete the journey. Sightseers are also carried over the canyon by helicopter.
The canyon was first seen by a European in 1540, García López de Cárdenas[?] from Spain. Beginning long before that, the area was inhabited by Native Americans who built settlements in the canyon walls.