When Rebecca Giggs encountered a humpback whale stranded on her local beach, she considered how whales could shed light on the condition of our seas. Fathoms: the world in the whale is her stunning meditation on the lives of these awe-inspiring creatures and her exploration of what they reveal about us. In the spirit of Rebecca Solnit and Rachel Carson, Rebecca – whose work has appeared in Granta and The New York Times – writes vividly about the natural world. In conversation with Angus Dalton, Rebecca asks what it means to write about nature at a time of environmental crisis.