Narrator and character (Dramatic Irony)
Strayed's status as both character and narrator create many opportunities for dramatic irony throughout the memoir, when the author clues the audience into something the character doesn't know. For instance, at the end of the novel, when Cheryl The Character has conquered the PCT and is feeling independent, Cheryl The Narrator tells the audience that she will also go on to cultivate healthy, positive relationships with a husband and children.
The real danger on the trail (Situational Irony)
On a wild trail that boasts the risks of rockslides, bears, and more, it is tragically ironic that the most danger Cheryl faces is from two threatening men—rational beings who, by all accounts, should know better, yet who clearly have no concept of how to respectfully treat a woman traveling alone.
Strengthening relationships through solitude (Situational Irony)
One might expect that improving relationships requires actually working through with other people; it is ironic, therefore, that Cheryl seems able to improve her relationships with everyone from men, to her family, to even her dead mother by spending intentional, extended time in solitude.
The lack of condoms (Situational Irony)
For most of her journey, Cheryl carries first a roll of condoms, and then just one. She is hoping that she will eventually meet a lover somewhere on the trail. This stubborn insistence on keeping a condom with her, even though it seems increasingly unlikely that she will need it, creates expectations in a reader that Cheryl is eventually going to come across a willing partner. However, when she finally goes on a date with Jonathan in Ashland, Cheryl purposefully leaves her condom at her hostel. Ironically, when things take a turn for the sexual, it turns out that Jonathan does not have any condoms. This comical situation contrasts with readers' expectations: Cheryl had been ready for a sexual encounter for so long, but when one occurs, she is not prepared.