The Plunge: Maverick Swimmers, An Unlikely Quest and the Transformative Power of Cold Water By Chris Ballard Viking, 320pp, £22When 19th-century US naturalist Henry David Thoreau expounded simple living in his classic, Walden, his regular cold water dips were “a religious exercise, and one of the best things which I did”. Who knows what Thoreau would have made of Dryrobes and beach saunas, or US sports journalist Chris Ballard’s exploration of ice swimming? Seeking a cure for his athletic injuries, Ballard’s research led him from freezing fjords to alpine lakes to the Extreme Environments Laboratory at the University of Portsmouth. He talked to ice milers, including Ireland’s Ger Kennedy, met people with serious illnesses who say cold water changed their lives, took to ice swimming, representing the US, and ended up in an ambulance at one point. A compelling exploration of what he calls “Nature’s cocaine”. Lorna SigginsNow Burns Blue By Cenac Rollins Somesuch, 296pp, £9.99 It’s a London summer and Frank and Afia are already over. As carnival approaches, they know their paths will cross for a final time. They are determined to see change in the world, though they disagree on how: lawyer Frank believes in reforming from the inside, while Afia is committed to challenging the whole system. Let the whole thing collapse, for all she cares. Now Burns Blue is a debut as dark as it is funny. Rollins’s dialogue is colourful, rich and gritty. Even when it is a mumbled exchange of teenagers fumbling through a drug deal, Rollins breathes life into every line, creating a portrait of London that is as vibrant as it is unsettling. John O’Connor Everything To the Sea By Alicia Upano Bloomsbury, 300pp, £20The Hawaiian writer’s debut novel is a sweeping romance that touches on fate, tragedy, betrayal and reconnection. When architecture student Jane Ito returns to her hometown of Hilo for the summer, she falls in love with former schoolmate Kenji Lee, convincing him to join her in Honolulu. They are barely there, however, when a tsunami devastates Hilo, the duo watching the disaster unfold in real time on TV. Kenji returns immediately, eager to help in any way he can. Jane can’t face going back, sparking another tectonic rift, this time in their relationship. It isn’t until seven years later that their paths cross again, Kenji eventually approaching “this tender creature – love, some might call it – sideways, as if not to scare it”. Impressive without being overwrought. John Walshe