Deep within this book is this hint of a personal family memoir as told through the great swimming escapades of her life – “I swam from Alcatraz on a dare. I was across a lake on my wedding day,” she writes. She brushes against that story rather than exploring it fully, and reading the book you can’t but feel that there is a vital personal memoir locked within. But it’s not the book she set out to write here. While Tsui’s personal relationship with water is a guiding tread through oceans and thousands of years, the book itself is almost structureless from chapter to chapter, moving from Lord Byron’s famous swim across the Hellespont to the prisoners at Alcatraz who tried to navigate the treacherous swim across to San Francisco.