«Eminently readable» – The TLS Books of the Year, 2024. Ocean is an ambitious history of the pre-Columbian Atlantic Ocean, a narrative that begins with the formation of the mid-Atlantic ridge about 200 million years ago and concludes with the conquest of the Canary Islands by the Castilians in the 15th century, which provided a model for the methods used by the Spanish in the colonization of the New World. John Haywood argues that the notion that the history of the Atlantic begins with the first voyage of the famous Genoese sailor is mistaken, and that the maritime and shipbuilding skills that allowed Europe's global exploration and expansion were not developed in the 15th century but were acquired over centuries and thousands of years in the Atlantic and regional seas. The story of the pre-Columbian Atlantic is the narrative of how Europeans learned to dominate the oceans, which is critical to understanding why it was Europeans, and not any other seafarers of the world, who "discovered" the world.

Ocean is influenced by the author's extensive travel experiences in the Atlantic region, crossing the Grand Banks of Newfoundland, the Sea of Darkness, and the marine vegetation of the Sargasso, reaching locations such as Vinland, Greenland, the Faroes, and the Cape Islands. Featuring a multitude of sailors, fishermen, monks, traders, and visionaries, this is an in-depth history of a neglected subject, merging geology, geography, mythology, cosmology, evolving maritime technologies, and the early history of exploration to tell a fascinating and engaging narrative that lies at the heart of modern Europe's history and its relationship with the rest of the world. A large-scale history, Ocean offers the reader a rich historical narrative that will appeal to readers of David Abulafia, Simon Winchester, and Michael Pye.