Take a look at the shirt or jeans that you're wearing. How did it get to the store where you purchased it?
For most products, they're shipped by boat -- 90 percent of the world's goods get to where they're going by sea.
Rose George, author of "Ninety Percent of Everything: Inside Shipping, the Invisible Industry That Puts Clothes on Your Back, Gas in Your Car, and Food on Your Plate" spent time on a shipping vessel to better understand the journey, and "human element," that shipping requires.
"The shipping industry has this odd term for the people who work at sea, they call them the 'human element,'" George says. "It is a very strange term, I've yet to come to terms with it."
And the 'human element' mostly comes from the world's developing countries. "The people who work in ocean-going shipping ... are probably not American, and they're probably not British or Western European. They're probably going to be Eastern European or Indian, and the crew are overwhelmingly likely to be Filipino because Filipinos make up a quarter of the world's crew," George says.
That life at sea can be difficult in different ways.
"[Shipping workers] feel a bit disregarded. It's the second-most dangerous occupation on the planet after fishing. They're working in the planet's wildest place, the ocean. We use it for leisure, we go cruising in great numbers, but generally we fly over it," Goerge says. "It's a patch of blue on an in-flight electronic map, and it's not really a place of work and industry."