The Outrun by Amy Liptrot

At the age of thirty, Amy Liptrot finds herself washed up back home on Orkney. Standing unstable on the island, she tries to come to terms with the addiction that has swallowed the last decade of her life. As she spends her mornings swimming in the bracingly cold sea, her days tracking Orkney's wildlife, and her nights searching the sky for the Merry Dancers, Amy discovers how the wild can restore life and renew hope.