Family Dysfunction
The complex and largely dysfunctional relationships among members of the Curren family are a major thematic focus in Past the Shallows. The nuances of a dysfunctional family dynamic are most evident in the way Miles relates to different members of his family. While Miles feels genuine care and a sense of duty in regards to Harry, he also feels the burden of having to protect Harry from Dad's violence and neglect. Because Miles depends on Dad for shelter and food, he develops a high tolerance for Dad's abusive behavior, instinctively working to appease Dad's moodiness and get out of the way when he drinks. Miles also has a complex dynamic with his older brother Joe, who Miles resents for abandoning a family that Miles hasn't given up on. In this way, Miles plays a rescuer role with his little brother, a victim role with his older brother, and a people-pleasing role to counteract the unpredictable nature of his father. Ultimately, the roles Miles occupies are expressions of a dysfunctional dynamic in which Miles neglects his own needs in order to react to the feelings and actions of the people in his family.
Trauma and Memory (Dissociative Amnesia)
Memories of the traumatic night Mum died resurface throughout Past the Shallows, establishing the link between trauma and memory as a dominant theme. Because Harry and Miles were in the backseat of their mother's car on the night she crashed it and died, they retain memories of the traumatic incident. However, they re-experience the trauma of the crash differently. Harry, having been only a toddler, doesn't remember scenic details of the crash; rather, the feeling of the crash lives in his body as a feeling of sickness he experiences in Aunty Jean's car as they drive past the spot Mum died. Miles, being older, is able to slowly piece together a visual and auditory picture of the crash. The fact that he cannot recall the complete memory from the outset of the book is a result of his memory having selectively blocked out the traumatic incident. Experiencing a condition known as dissociative amnesia, Miles instinctively repressed his memory so that he wouldn't have to confront the unpleasant truth that he witnessed Dad take part in Mum's and Uncle Nick's deaths.
Grief
Another of the novel's major themes is grief. Having lost Mum and Uncle Nick on the same night, and later Granddad as well, surviving members of the Curren family and people in the community of Bruny react to and cope with grief in different ways. While Dad takes his resentment out on his children and descends into alcoholism to mask his pain, Joe avoids confronting his grief by planning to set sail and leave town. Aunty Jean sees the genes of her sister when she looks at Harry, but otherwise bottles her emotions and feigns normalcy for Harry's sake. Miles meanwhile represses the memory of the night his mother and his uncle died, as he tries to focus on looking after Harry, not angering his father, and enjoying a surf when he has the time. Ultimately, Parrett depicts through the different characters' responses to grief how humans have little guidance about how best to continue with their lives when death is brought to the forefront of their concerns.
Parental Abuse
With Parrett's unflinching depiction of Dad's neglectful habits, physical abusiveness, and tendency to emotionally manipulate his children, Past the Shallows centers parental abuse as a major theme. Parrett tells the story through the perspectives of Miles and Harry, who experience the abuse largely as normal. As children, they know no other reality than life with a violent caregiver, and so their survival instincts prompt them to live in fear of their father's turbulent mood, avoiding doing anything that might anger him, and leaving the house for as long as they can while he is on a drinking bender with Jeff. Even after Dad allows Jeff to force-feed whiskey to Harry and assault Miles, Miles returns the next day to clean up the mess the men left in the living room and clean his own blood off the floor. Ultimately, Parrett's depiction of parental abuse illustrates how authority figures can so easily take advantage of an innocent and inherently trusting child who does not understand they are being abused.
Alcoholism
Interwoven with the themes of parental abuse and family dysfunction, the disease of alcoholism is another major theme in Past the Shallows. Although Parrett doesn't use the terms "alcoholism" or "alcoholic" even once in the text, Dad's behavior bears all the markers of alcohol addiction. Deeply resentful of other people and prone to outbursts, Dad neglects his children in order to drink heavily at the pub after work. He and Jeff also spend two days straight drinking—an event that is presented through Miles's perspective as being routine, as he knows to avoid the house as much as possible when Dad is so drunk. When Dad sobers up in the morning, he pretends as if nothing had happened, taking no responsibility for his outbursts and pattern of abuse. Through this portrait of a raging alcoholic parent, Parrett shows the emotional strain to which Dad subjects his son.
Economic Strain
Another of the novel's dominant themes is economic strain. Early in the novel, Parrett drops hints that Dad is feeling financial pressure with diminishing abalone catches and the debt he incurred after buying out Uncle Nick's investment in the fishing boat at Aunty Jean's request. Economic strain increases Dad's stress level and provokes him to begin poaching abalone from protected waters and fishing without a license. Their father's poverty also impacts Miles and Harry, as Miles is forced to work as an unpaid laborer on his father's boat while Harry is left without childcare or an adequate and stable food supply. The theme of economic strain also contributes to a chain of crucial plot developments, as Dad's desire to get the boat back out on the water after it is damaged without fully repairing it results in the engine cutting out while Jeff and Dad are diving—an event that sets in motion the climactic scene in which Dad assaults Miles and then pushes Harry over the railing and into the water.
Refuge
The last of the novel's major themes is refuge. Knowing instinctually that they are not safe around their father, throughout the book Miles and Harry seek refuge with family, friends, and, in Harry's case, a stranger. Miles's usual refuge is to surf with his older brother Joe. When they are together, Miles's anxiety level goes down and he can enjoy catching waves. Harry seeks refuge by spending time with Aunty Jean and Stuart, but he spends much of the novel going by himself to George Fuller's property. Although Harry just met George, the two form a quick bond as George teaches Harry about the landscape and provides nurturing food and warmth. Refuge also arises as a theme in relation to Joe, who left the abusive Curren home at thirteen to live with his grandfather. By the end of the novel, Parrett shows the full significance of the theme of refuge by revealing that Mum and Uncle Nick were eloping with Miles and Harry on the night the car crashed: they too were seeking refuge from Dad, leaving the island of Bruny to start a new life in the Tasmanian capital city of Hobart.
