Well, it's mostly about the fish... However, I get a great deal of satisfaction engaging, observing, interpreting and appreciating the natural world around me when I am on the water. And yesterday was especially rich.
In addition to tempting a goodly number of cutthroat to hand on the fly, I also experienced:
Largescale suckers and the little puffs of sand as they fed along the bottom
Broken shells of Canada goose eggs
Game trails in the long grass
Fresh bear scat. I know it was fresh cuz I poked at it with a stick
The head of a chub in the shallows (what predator leaves just the head? Otter?)
Sticks stripped of bark, a beaver's snack
Shorn grass at the water's edge (presumably by feeding deer, maybe bear)
Upstream, a pair of Canada's started honking. I suspected something was alarming them, was looking to see what it was, and a coyote crossed the stream
A male Canada that led me downstream while his partner hid in the grass with her neck arched over so I wouldn't see her
Deer and bear tracks in the sand
As I was walking a game trail along the flood plain, I heard some noise up the steep bank and back into the dense brush. I stopped. There were a couple of sharp cracks of branches being snapped (under seemingly heavy foot) and then silence. I stayed still for a looong time waiting for more snaps, looking into the bush, wondering if I could see something, hoping I wouldn't. No more noise. Yeah, I was unnerved.
Later, while I was still jumpy from this, a trio of ducks landed in the water behind me and almost gave me a jammer.
So yeah, apart from being scared sh!tless, it was a rewarding day of hunting my quarry and paying attention to the rich diversity and to the signs of the unseen.