Converging currents at the surface of the ocean create some of the best places to find life. It's there that tiny plankton hang out—and where plankton float, hungry fish follow.

It's also there that researchers are finding a new, and now ubiquitous, ocean resident—plastic.

“To me it's a little shocking how much is in relatively small samples,” says photographer and National Geographic Explorer David Liittschwager. Last July, Liittschwager accompanied scientists sampling waters off the coasts of Hawaii, where currents converge to form slicks full of plankton. Using nets, they scooped 400 cubic meters of surface water into simple five gallon buckets and hauled it back to a lab on Hawaii's Big Island.

In addition to photographing water samples from Hawaii, Liittschwager