Below is a video from YouTube channel What The Physics?! shows Greg Kestin, a theoretical physicist researcher at Harvard University simply pouring a tablespoon of olive oil into the middle of a lake, he first shows and then explains how oil floats on the surface of the water. It begins to spread until it creates a layer literally one molecule thick. Curiously, this layer appears to calm the waves of the lake caused by the breeze. As Greg points out, if you measure the size of the still water without waves, you can work out how big one molecule is.