One of the greatest views of the Colorado River in Grand Canyon is found here some 500 ft.(150m) above the river at Nankoweap.
Virtually all raft trips stop here, and the passengers make the climb up to the Anasazi granaries (I'll post an image of these eventually). Those that make the climb are rewarded with this spectacular downriver view.

I've stopped here on river trips, but for most of my Nankoweap shots are the result of hiking the the incredibly grueling Nankoweap Trail (14 miles, 23 km from rim to river)--the most difficult of all named trails in Grand Canyon.

The greenish color of the river is the result of the Glen Canyon Dam (Lake Powell) some 67 miles (100km) upstream. The huge amount of sediment the river once carried giving it a deep brown/redish color is now trapped behind the dam. Without the light blocking sediment, sunlight can now reach deep into the river creating an environment for algae and river plants to flourish. Only when side canyons (eg., Paria Creek, Little Colorado River) below the dam flood does the river regain something of it's original 'colorado' (colored) nature.

The sheer redish walls in the upper left are called Redwall. They are not red naturally, but are stained red by rock layers above. There is an image in my gallery from the Redwall Cavern (River MIle 33). There the Redwall is at river level. Now, just 20 miles later, that same Redwall is 500 ft. above the river--strong visual evidence of the river cutting down thru the earth exposing the layers below (actually cutting down against uplift of the land).