Towering sand dunes that ripple across the heart of a 3.4-million-acre landscape, hidden canyons that echo with splashing, gurgling water that nourishes a surprising cache of lush vegetation, a human history of anguish as well as prosperity. The surreal landscape of Death Valley can be deadly hot in summer, and yet it is one of the more intriguing units of the national park system because of its stark beauty and demanding nature.