In 1991, Curtis Ebbesmeyer was a successful middle-aged oceanographer who had studied offshore oil platform design in the North Sea, sewage dispersion in Puget Sound, and eddies in the North Atlantic. But he found his true calling when thousands of Nike shoes, which had spilled from a cargo vessel crossing the Pacific months earlier, started washing up on Northwest beaches. Fascinated with all kinds of "drifty things," Ebbesmeyer saw the shoes as a unique opportunity to study the oceans.
"These thousands of lost sneakers composed a giant scientific experiment on a silver platter, fully if unwittingly funded by Nike – a serendipitous window into the ocean's deepest secrets," Ebbesmeyer recalls.
In Flotsametrics and the Floating World, co-written with journalist Eric Scigliano, Ebbesmeyer describes how he has used flotsam (floating objects accidentally lost at sea), including shoes, plastic bath toys, Japanese urns, and human body parts, to map and time ocean currents. Knowing when objects fell overboard and when they washed ashore, Ebbesmeyer and his colleagues could test computer models of ocean circulation and calculate how long it took objects to travel all the way around gyres – huge closed current loops that rotate in the middle of the world's major seas.
Ebbesmeyer coined the term "garbage patch" to describe zones of floating junk that have formed at the centers of most of the world's 11 ocean gyres. Media accounts usually focus on one patch in the western Pacific, but Ebbesmeyer has documented eight garbage patches around the globe. Combined, he estimates, they would cover an area more than twice as big as the continental United States.
As Ebbesmeyer recounts, humans have been throwing stuff into the oceans for centuries. Byzantine emperors beheaded their defeated opponents and threw their corpses into the Bosporus Strait. Norsemen tossed their favorite possessions overboard in the 9th and 10th centuries and settled where the goods washed up — the modern site of Reykjavik. This was good science, Ebbesmeyer observes: If flotsam from ships washed up there, so would usable stuff like dead whales and driftwood.
More recently, the Guinness brewery dropped 200,000 bottles containing commemorative messages into the Atlantic and Caribbean to mark the company's 200th birthday in 1959. And religious evangelists have thrown thousands of "gospel bottles" into the seas to reach potential converts. Even when senders' motives are a little strange, these launches are useful data sources for Ebbesmeyer, who reviews the available historical data on 32 drifter launches that took place over the past 150 years from locations around the world. (Response rates varied from 1 to 50 percent, depending on where the bottles were launched, what reward they offered for a reply, and how well they were sealed and weighted.)
In sum, flotsam can tell us a lot. An increasing share of ocean junk is plastic, which lasts longer than paper, wood, cloth or metal, although it breaks down into increasingly tiny fragments. Sometimes these bits choke marine animals and birds. Many contain phthalates and other endocrine-disrupting or toxic components, which can kill or alter sea life more slowly. Thanks to quirks in coastal topography and ocean currents, some "junk beaches" accumulate tons of plastic waste every year.
"Sometimes I feel like an albatross myself, choking on so much grim but exquisite data gleaned from the waves," Ebbesmeyer ruefully observes. As one response, he argues that shipping companies should have to report anything they lose or throw overboard. (This is required now only when ships lose at least eight freight containers, because spills on this scale are considered threats to navigation.)
Flotsametrics is full of insights about how the oceans have shaped human history. For example, Columbus made good time across the Atlantic because he picked up the Atlantic Equatorial Current, which moves ten miles per day. And some of the first Japanese settlers in Hawaii arrived there because their fishing boats were pushed out into the Pacific by powerful coastal currents.
It's also a window into the mind of a curious scientist, always looking for new angles on the "floating world," with vivid descriptions of how oceans and currents work. Ocean waters contain numerous blobs and slabs of water with varying densities and temperatures, which the authors compare to a huge, flattened lava lamp. "If each slab were a different color, the ocean would look like a Pointillist painting," they write. And the Gulf Stream "shakes loose like a fire hose from its pivot point at North Carolina's Cape Hatteras, spraying uncountable drifting objects east toward Europe."
This exuberant book will make you want to kick off your shoes and go beachcombing. If you turn up anything interesting, you can report it to a citizen-science network that Ebbesmeyer helped create to collect information on flotsam finds (their newsletter, Beachcombers' Alert!, is online here ).
Freelancer Jennifer Weeks  is based in Watertown, Mass.
** From SEJ's quarterly newsletter SEJournal Summer 2009 issue