The Sun Also Rises by Ernest Hemingway (1926) — The novel that brought the Basque country to international attention. Hemingway based much of it on his own fishing and drinking trips through Pamplona, Saint-Jean-de-Luz, and the hills behind Biarritz. The Basque fishing villages, the festivals, and the landscape in the background of the novel are still recognisable today.
Homage to Catalonia by George Orwell (1938) — Strictly speaking about the Spanish Civil War, not Biarritz, but the French Basque country served as the crossing point and refuge for many who passed through this period. Reading it illuminates why the Spanish–French border area looks and feels the way it does.
A Life Well Lived: Surfing and the Basque Country by multiple authors — A coffee-table book on the history of Basque surfing, with photographs tracing the sport from Viertel's first board in 1956 to the present professional circuit. More useful as context than as literature, but the images tell the story.