The simile in the third stanza affects the poem because;
Simile is a figure of speech where two words that share some similarities are directly compared using 'like' and 'as'.
In the third stanza of the poem, "The Cremation of Sam McGee", the poet likens the harsh cold in the arctics to the driving of a nail.
A nail is a sharp object which when driven into the body or a surface can result in pain.
So, in comparing the icy North to the driving of a nail, the poet was referring to the physical and mental pain that was caused by the brutal conditions in that space.
Learn more here:
https://brainly.com/question/12739087