Scientists studying glaciers in Greenland had a problem. Meltwater often ran into channels within or under the glacier, and they didn't know where it came out, an important data point in understanding the effects of increased melting on the Greenland ice cap as a whole. There was no budget for anything like miniature robotic vehicles, which likely would not have survived anyway. The solution? Dump 90 $2 toy rubber ducks into the water. The ducks have vanished into/under the glacier, and Dr. Alberto Behar and his colleagues are waiting for someone to find them. The ducks may travel 30 miles to open water, or they may be stuck or diverted along the way. It's data either way, and this episode is a great example of human ingenuity at work.
UPDATE: As of December 24, no ducks have been recovered. This is disappointing, but they may yet surface, and even if they don't. showing there is no passage under the ice to the bay is still important information.