As you probably know already, the Amazon river is the largest river system in the world – by extent of watershed, by volume of water, and by some measures distance from the sea to its furthest tributary source.
We sailed offshore from Brazil, out of sight of the shore. We saw the color of the ocean change from deep blue to coffee-brown a day before we saw the river shore. The volume and force of the outflow of the river turns the ocean fresh for many miles beyond the coast.
The distance from the mouth of the Amazon to its Andean sources is about 4,000 miles. That is the width of the continental US. We sailed about 1,000 miles up the river to the city of Manaus. There is another 3,000 miles more beyond Manaus. Imagine one tropical forest and river system from Sacramento to Washington DC. Hard to comprehend.
The part of the basin where we sailed is for the most part flat. From the ship, we saw a large foreground of sometimes brown water, sometimes black water; a thin strip of green, just a tree tall; and huge sky above. Not as dramatic as a fjord or a river in a gorge. We had to reflect on where we were, and on the immensity of forest beyond.
It is amazing that you can call up Google Maps even in the Amazon. When you choose satellite view, you see that beyond the forest front there is sometimes only more forest, and often there is a patchwork of cleared land and soybean fields (at least where we were). Settlements are few, strung together with a few roads.
Our guide on a forest walk, who is from an indigenous tribe, said that his village is something like 2,000 km away; only about half of the length of roads between Manaus, in the center of the Amazon basin, and his village are paved. Imagining the immensity of the Amazon is a challenge; seeing in the satellite view of Google Maps the amount of deforestation is stunning.
Examples of the forest at the edges of the river: