The best examples of nature in any form in Nathaniel Hawthorne's The Scarlet Letter are found in the forest, the place where "good" Puritans never venture. The forest is a place where evil abounds and where sinners dance with the devil; therefore it is not surprising that Hawthorne uses imagery, and particularly personification, to bring the forest to life for his readers.
One day Hester and Pearl are on a walk.
The road, after the two wayfarers had crossed from the peninsula to the mainland, was no other than a footpath. It straggled onward into the mystery of the primeval forest. This hemmed it in so narrowly, and stood so black and dense on either side, and disclosed such imperfect glimpses of the sky above, that, to Hester’s mind, it imaged not amiss the moral wilderness in which she had so long been wandering.
Hawthorne compares this primitive and wild path path Hester is walking to her own path of sin and shame, calling it a "moral wilderness." This is an example of personification since, clearly, a natural (non-human) element does not have a moral identity. The quote continues:
The day was chill and sombre. Overhead was a gray expanse of cloud, slightly stirred, however, by a breeze; so that a gleam of flickering sunshine might now and then be seen at its solitary play along the path. This flitting cheerfulness was always at the farther extremity of some long vista through the forest. The sportive sunlight—feebly sportive, at best, in the predominant pensiveness of the day and scene—withdrew itself as they came nigh, and left the spots where it had danced the drearier, because they had hoped to find them bright.
Here is an image of the sun, splaying and dancing across the path and through the trees of the forest that line it. This imagery also serves as a symbol throughout the novel, as the sunshine constantly seeks Pearl but flees from Hester.
When Hester and Dimmesdale finally meet in the forest, the brook serves as some kind of dividing line between the old and the new, the past and the future.
All these giant trees and boulders of granite seemed intent on making a mystery of the course of this small brook; fearing, perhaps, that, with its never-ceasing loquacity, it should whisper tales out of the heart of the old forest whence it flowed, or mirror its revelations on the smooth surface of the pool. Continually, indeed, as it stole onward the streamlet kept up a babble, kind, quiet, soothing, but melancholy, like the voice of a young child that was spending its infancy without playfulness, and knew not how to be merry among sad acquaintances and events of somber hue.
This brook talks (personification) and is compared to a young child who is too sad to play (simile).
Hawthorne also refers to the "untamed forest" and says "the deep heart of Nature could pity and be kind" when he describes the rose bush outside the prison. It is clear that Hawthorne sees the forest and other elements of nature as being actors, fellow participants, in the drama that unfolds before it.