Pumpkin Spring is a geothermal mineral spring in Arizona’s Grand Canyon near the Colorado River, notable for its bright orange mineral and organic deposits. Water rises in a pool ringed by travertine atop a mineralized carbonate mound, then spills toward the river. Although the spring emerges at about 23 °C and is identified as a hot spring, its most remarkable quality is its vivid appearance and unusual chemistry. The water contains extremely high arsenic levels as well as zinc, lead, and copper, making it among the most poisonous waters in the Grand Canyon. Its significance lies in its distinctive mineral-built form rather than recreation.