The largest national park south of Alaska, Death Valley is known for extremes: It is North America's driest and hottest spot (with fewer than two inches/five centimeters of rainfall annually and a record high of 134°F), and has the lowest elevation on the continent-282 feet below sea level. Even with its extremes, the park still receives nearly a million visitors each year.In 1849 emigrants bound for California's gold fields strayed into the 120-mile long basin, enduring a two-month ordeal of "hunger and thirst and an awful silence." One of the last to leave looked down from a mountain at the narrow valley and said, "Good-bye, Death Valley."The moniker belies the beauty in this vast graben, the geological term for a sunken fragment of the Earth's crust. Here are rocks sculptured by erosion, richly tinted mudstone hills and canyons, luminous sand dunes, lush oases, and a 200-square-mile salt pan surrounded by mountains, one of America's greatest vertical rises. In some years spring rains trigger wildflower blooms amid more than a thousand varieties of plants.Native Americans, most recently the Shoshone, found ways to adapt to the more recent and forbidding desert conditions that exist here now. Rock art and artifacts indicate a human presence dating back at least 9,000 years.