Twain's book Life on the Mississippi gives us the most comprehensive picture of what a riverboat pilot's life was like, especially because Twain himself was a licensed pilot and identified with the riverboat life his entire career.

Riverboat pilots, particularly on major rivers like the Mississippi, were the most respected people on a riverboat's bridge because their ability to "read" the river as it shifted its course from one minute to the next kept the riverboat from running into something that was going to, in their words, "kill" the boat.  When a pilot took a riverboat down the Mississippi, say from Vicksburg to New Orleans, he would encounter a set of obstacles.  Conditions on the river shifted so much, though, that when he reversed his course and went up the river, by that time he was presented with a whole new set of obstacles that he had to steer around.

There's a short section in Life on the Mississippi in which Twain discusses how beautiful the river looked to him before he learned how to be a pilot--he saw beautiful sunsets, swirling colors in the river, picturesque trees.  After he learned piloting, though, he learned to see all these things as potential threats to the boat, and, for him, the beauty of the river disappeared.