YOU’D think the market for books about personal crises resolved by communing with nature in the wild spots of Orkney would be fairly niche. Yet, just over a year after Amy Liptrot’s Outrun charted her battle to overcome alcoholism while spending two winters on sparsely-populated Papa Westray, we have Victoria Whitworth’s Swimming With Seals.

Whitworth too looks to the beautiful but unyielding landscape as an escape from a series of calamities. Her mother’s death, a stultifying, misjudged marriage and an absence of religious conviction have left her exiled from herself, like The Wanderer, the rootless hero of the Old English poem, whose lamentations for a life long gone form a haunting soundtrack to the memoir. But any suspicion Swimming With Seals might be riding on the coat-tails of Liptrot’s success is quickly dispelled; her preoccupations and style are sufficiently individual to ensure she stakes a distinctive literary claim on the archipelago.

A historian specialising in death and burial in the early Middle Ages, Whitworth has married while still in mourning, and moved to Orkney with her husband – a former monk – and young daughter. Soon, though, she finds her identity under threat from the weight of expectation attached to the words “wife” and “mother.” Having converted to Catholicism, she realises too late that an intellectual interest in religion is not the same as being religious, and that, however much she feels the “tug of faith”, faith itself will continue to elude her. Still playing the role of the devout partner, she compares herself to a hermit crab that has outgrown its borrowed shell, but still lugs it along, “clinging to the illusion of protection it affords”.

By the time the book opens, the only relief Whitworth has from the flattening effect of her own unhappiness, and the plantar fasciitis that impedes her walking, is swimming off the Sands of Evie and other beaches. She swims obsessively all year, without a wet suit, in temperatures as low as 5C. This act of potential self-harm releases endorphins, taking her close to “jouissance” – a trangressive, almost sexual zone where pain and pleasure meet. At the same time as sharpening her sense of her own physicality, swimming allows her to experience what Romain Rolland described as the “sensation oceanique” – a surrendering of the ego to the greater power of the universe, which he regarded as the wellspring of all spirituality.

Feeling such oneness with the water leads Whitworth to ponder the many myths that have been spawned by mankind’s maritime yearnings – the tales of mermaids and of selkies who shed their sealskins to come on shore to seduce or be seduced by humans. She would like to believe in writer Elaine Morgan’s acquatic ape theory – which posits that homo sapiens were once as at ease in the sea as on land – not only because it chimes with her own attraction to water, but also because it replaces “man the mighty hunter” with “mama, the mighty gatherer”.

The book is at its most interesting when Whitworth is using myths to interrogate female experience. Lost in the haar of her own depression, she empathises with Hans Christian Andersen’s Little Mermaid, who gives up her tongue in exchange for legs and a shot at winning the love of an earthbound prince. The prince makes her dance for him (and she does it, though every step is like treading on broken glass) before casting her aside for another woman. The author feels a kinship too with Persephone, the Greek goddess abducted by Hades and fated to spend six months a year in the underworld. For St Tredwell’s decision to gouge out her own eyes rather than succumb to an unwanted suitor, she appears to have a grudging respect.

It seems odd and a little unfair that – in a memoir exploring the challenge marriage poses to one’s sense of self – Whitworth should have allowed her husband’s perspective to become so submerged. Perhaps she feels she has no right to speak for him, but, though his presence is felt as a negative undercurrent, he surfaces less regularly – and makes less of an impression – than the curious seals. While relating to Whitworth’s misery, I couldn’t help but wonder how it felt for this faceless man, caught adrift with a wife who sought him out in grief and now sneaks off for illicit trysts with her paramour: the sea.

Whitworth’s field of expertise and her location – an island chain full of Neolithic, Norse and early Christian burial sites – mean she is ideally placed to ruminate on the passing of her mother and the role of ritual. A true academic, she eschews easy sentimentality, pointing out that – though she has placed an Afghan blanket and a book in her cardboard coffin – her mother will one day be nothing more than bones and red plastic buttons; just DNA for a future generation of archaeologists to analyse. It is left to the warrior from The Wanderer, who hears the voices of the dead in the cry of gulls, to communicate her despair; her emotional “fimbulwinter”. “All is wretched here, shaped by inexorable fate,” he says. “Wealth is on loan, friends are on loan, here man is on loan, kinsmen on loan, all the substance of this earth falls into the void.”

Though the author’s descriptions of the coastline in Orkney and the savannah in Kenya, where she spent some of her childhood, are sharp and original, some people may find Swimming with Seals too allusion-heavy for their tastes. Others will enjoy wallowing in the richness of her theological, philosophical and literary knowledge.