It takes skill to write an engrossing book about a “squat gray vessel” that, despite being the length of a football field, doesn’t even have a motor. Ian Kumekawa pulls it off, though, in Empty Vessel: The Story of the Global Economy in One Barge (Knopf, May 6), his superb account of a decades-old barge that holds much history—and is a portal into the secretive realm of international trade. “Kumekawa weaves in lucid and eye-opening explanations of the murky worlds of tax havens and loose regulations,” says our starred review. “The barge is at the heart of it all.” Kumekawa is a fellow at the Center for History and Economics at Harvard University and a lecturer in history at MIT—not far from the Atlantic Ocean, the vast body of water where his titular vessel has spent much of its exceptional life. Empty Vessel is one of our Best Nonfiction Books of 2025, and Kumekawa answered our questions by email.

What was the original idea that started you working on the book?

The idea came from my wife, who is a public defender. We were living in New York, and she had clients who were incarcerated on what was called “the boat,” a jail barge floating in the East River off the Bronx. I’m a historian of the British Empire, and the barge immediately called to mind the hulks that were a staple of the British penal system in the 18th and 19th centuries. I couldn’t believe there was still a jail ship operating in New York in 2020. I started looking into the history of jail barges in New York, and [as] I learned more, I realized that the history of one of those barges was almost too remarkable to believe. The result was Empty Vessel.

What inspired you during the writing of the book?

I read a bunch of books that took place at sea: Moby-Dick, B. Travens’ The Death Ship, David Grann’s The Wager, Maya Jasanoff’s The Dawn Watch, even Death on the Nile. Ships are great narrative devices for connecting disparate places and people.

Where and when did you write the book?

In general, I find writing quite difficult. The one rule I have for myself is that if I have a paragraph-size idea in my head, I have to stop everything and write it down. Much of the first draft of this book was written in paragraph-size spurts, mostly in my office, but in other places, too: libraries, archives, in the homes of friends and family, even typing with thumbs while sitting on the bus.

What was most challenging about writing this book? And most rewarding?

Researching the offshore world is hard because it’s designed to be obscure. Many of the traditional sources that historians use to study the past are unavailable or inaccessible. One way I tried to get around this problem was by talking to people who had lived, worked, or been incarcerated on the barge. This was the most rewarding part of the research process. During the pandemic, while I was stuck at home, I did a lot of Zoom interviews with other people around the world who were also stuck at home. It was a reminder of how small the world was and how global an experience could be.

What books published in 2025 were among your favorites?

I really appreciated The Lost Orchid by Sarah Bilston. And I’m so looking forward to reading Bench Ansfield’s Born in Flames.

John McMurtrie is the nonfiction editor.