What is a metaphor in chapter 31 of Huckleberry Finn

"Shut in like a tunnel"

"One morning, when we was pretty well down the State of Arkansaw, we

come in sight of a little one-horse town in a big bend; so we tied up

about three-quarters of a mile above it, in the mouth of a crick which

was shut in like a tunnel by the cypress trees, and all of us but Jim

took the canoe and went down there to see if there was any chance in

that place for our show."

"whooping and yelling like an Injun"

"Boggs comes a-tearing along on his horse, whooping and yelling like

an Injun, and singing out: 'Cler the track, thar. I'm on the

waw-path, and the price uv coffins is a-gwyne to raise."