The Subway Narrows in Zion National Park, along the Left Fork of North Creek, is both a brutal and spectacular hike not for the faint hearted.  Pools the size of hot tubs graced with the fall colors of cottonwood and oak leaves greet a weary canyoneer.  A little cool for fall swimming, but refreshing with the hot days of summer.  No matter the temperature the pools feel good on quivering calf muscles.