The major river that flows through the Grand Canyon is the Colorado River. This river, originating in the Rocky Mountains, cuts through layers of rock, creating the stunning and iconic landscapes of the Grand Canyon National Park. The Colorado River is approximately 1,450 miles long and is vital for the ecosystem and recreation in the region, offering opportunities for rafting, fishing, and hiking. The Grand Canyon itself is a UNESCO World Heritage Site, renowned for its immense size and geological significance, representing millions of years of Earth's history.