What are the metaphors in Rime of the Ancient Mariner, Part 2?

Part II, Metaphors:

And every tongue, through utter drought,

Was withered at the root;

We could not speak, no more than if

We had been choked with soot.

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The fair breeze blew, the white foam flew,

The furrow followed free;

We were the first that ever burst

Into that silent sea.