My son and I went down to Snake Road this weekend. This is in Larue Pine Hills, Illinois, in the Shawnee National forest.
The road has bluffs all along one side, and swampy wetlands on another. It is perfect snake territory. In the fall, snakes migrate from the swamps to the bluffs, where they will den up and mate for the winter. In the spring, they all migrate back out to the swamp. The Forest Service closes down the whole road during these migrations, except for foot traffic.
This year we saw 6 snakes, 4 of them Cottonmouths. We also saw a fox, a raccoon, 5 frogs, about 30 turtles, a milipede longer than my hand, and exactly zero squirrels, mice, or other small rodents.

Without further ado:

Yearling Cottonmouth, trying to find a den.

Black Rat Snake holed up in a tiny crack. Some crazy man told us to "Go off the path by the cliff before the water, then climb the rock, and look in the crack, and you'll find him." Worst directions ever, but we did it!

Ribbon Snake. Very friendly fellow.

Big Cottonmouth. Okay, my kid saw this guy from like 30 feet away, across a path, past me, and a couple feet into a mucky swamp. I was 5 feet away and couldn't see him till my kid pointed him out 4 or 5 times. And I had my glasses on. Sheesh.
Anyway, it was a grand old time, and we cooked stew over a campfire and swapped tall tales til we hit the sack in our cozy tent, and life was awesome.