The Gowanus Canal in New York City is known to be one of the most polluted waterways in the United States. You can imagine everyone's surprise, then, when an oasis of greenery was spotted sprouting on the surface of the river three weeks ago.

Not only is the brackish water's appeal improved with the improbable garden, the stream is being cleansed at the same time.

Called GrowOnUs, the project is an experiment in "floating infrastructure" that utilizes a process called phytoremediation to purify the waterway. Over thirty different kinds of plants act as sponges to clean, desalinate, and mitigate the chemicals affecting the murky canal.