Grand Canyon is one of the most vast, beautiful, easily recognized, harsh, and inspiring places on Earth. It is one of our planet’s few natural landmarks visible from outer space, and its magnificent panoramas, ecosystems, cultures, and history lure millions of visitors per year. Most of these visitors connect strongly with Grand Canyon from trails and overlooks on the rim. However, even these trails and overlooks can’t encompass all of Grand Canyon. Although abundant and stretching for hundreds of miles, trails span less than 25 percent of the rims along Grand Canyon, and many parts of GCNP remain virtually unexplored. Early visitors to Grand Canyon saw and interpreted the canyon in different ways. Native Americans were sustained by Grand Canyon, and they, in turn, protected and revered the land. The first known Europeans to see Grand Canyon arrived in 1540 (80 years before the Pilgrims landed at Plymouth Rock), when a detachment of Spanish soldiers led by Captain García López de Cárdenas reached the South Rim. Cárdenas and his men were astonished by the canyon’s size what appeared as small boulders were taller than the 342-foot-high Great Tower of Seville. Cárde- nas considered the canyon little more than an obstacle to finding the Lost Cities of Gold that he sought. There was virtually no more interest in Grand Canyon for more than 300 years, when—in 1857—an expedition led by Lt. Joseph Christmas Ives rode a steamboat up the Colorado River into part of the lower canyon. Although the expedition’s naturalist John Strong Newberry appreciated the canyon’s geologi- cal significance, Ives declared that the area was “altogether valueless” and, after seeing it, that there was “nothing to do but leave.” Until the 1860s, the Colorado River through Grand Canyon remained unex- plored because of its presumed dangers and remote location. The river’s large drop in elevation was assumed to mean that there were violent rapids and high waterfalls that would make navigation dangerous and difficult, if not impossible. In 1869, despite these presumed dangers, Civil War hero John Wesley Powell deci ded to run the Colorado River through Grand Canyon. Along the way, Powell and his crew experienced many hardships, and their task became increasingly diffi- cult. They knew the dangers ahead of them (Powell, 2013): And now we go on through this solemn, mysterious way. The river is very deep, the canyon very narrow, and still obstructed, so that there is no steady flow of the stream but the waters reel and roll and boil, and we are scarcely able to determine where we can go. . . . We can neither land nor run as we please. The boats are entirely unmanageable no order in their running Introduction