When thousands of rubber duckies fall overboard from a container ship en route to the U.S. from China, Hohn, an English teacher turned investigator of the high seas, tracks them down in Moby-Duck.

When did your interest in the lost rubber ducks become an obsession?

Like most obsessions I suppose, mine grew gradually and was kindled by frustration. It seemed so incredible, that I wanted to imagine it with as much verisimilitude as I could muster. When and where did the toys fall overboard? Where did they go, and why? And when I first heard the story, I was about to become a father. Childhood was much on my mind, and in the bestiary of American childhood, there is no creature more iconic than the yellow rubber duckie. I also was preparing to teach Moby-Dick. The incongruity of those yellow icons of childhood, made in China for the bathtubs of America, out there in Melville's sublimely inhuman wilderness of water seemed a kind of riddle.

What were the environmental issues you stumbled upon?

The trail of the toys soon led me to what has become colloquially known as the Great Pacific Garbage Patch. When I first heard of it, the Garbage Patch sounded fabulous, like something out of Jules Verne, a floating junkyard twice the size of Texas. The convergent currents north of Hawaii collect flotsam and jetsam, much of which these days is plastic, and unlike the wooden or metal or rubber flotsam and jetsam of the past, plastic can persist at sea for centuries. Eventually, sunlight breaks it down into fragments, but those fragments remain, flowing through the water column like dust. The currents there deliver more than 20 tons of plastic debris every year.

What was the most frightening moment of your quest?

I'm terrified of sharks. Diagnosibly phobic. At the Jersey shore, I won't wade in past my knees. South of Hawaii when we were supposed to search the water column for plastic with little green nets, I was hyperventilating before my flippers hit the water. I only lasted a few minutes. It wasn't just the idea of dangling there like shark bait. I'd been told that swimming in the tropical ocean feels like "swimming in the sky," an apt comparison that in some may inspire reverence but in me inspires a watery sort of vertigo. Melville would have understood: "Mark, how," he writes in Moby-Dick, "when sailors in a dead calm bathe in the open sea—mark how closely they hug their ship."

Are there still rubber duckies out there, bobbing along?

Thousands more are still out there, either adrift or marooned—and not just duckies, let's be clear. The bath toys came in sets of four. There were also red beavers, blue turtles, and green frogs. There have been sightings in the North Atlantic, one in Scotland, one in Maine. People in Alaska are still finding them.

How do you top the adventure that was Moby-Duck?

I'm working on something entirely different, a project that will require me to spend more time swimming through libraries than sailing through oceans. I'm done for now with seafaring, and with ducks.