Thanks to “Sesame Street,” everybody over the age of two knows that rubber duckies make bath time lots of fun — but who knew the little yellow guys could make oceanography a bit more fun, too? Eleven years ago, a shipping container carrying 29,000 rubber bath toys (frogs, turtles, and beavers, as well as the familiar duckies) fell overboard in a storm in the North Pacific. Now, the company that made the toys, The First Years, is offering a $100 reward to anyone who finds one. The goal of the reward program is to help scientists better understand how foreign objects and substances — from trash to oil — spread throughout the ocean. So far, hundreds of the toys have washed up on North Pacific shores, especially in Alaska; computer models suggest that others might make it as far as the North Atlantic or even the coast of Africa. Every year, 10,000 of the 100 million containers shipped by boat fall overboard. Thirty percent of all cargo shipped by sea is hazardous.