These plumes were caused in part by unprecedented amounts of chemical dispersants injected near the leaking Deepwater Horizon wellhead in an effort to better disperse the oil from forming big globs—much like grease-cutting soaps do for dirty dishes.

At the time when the plumes were first discovered, attention had focused largely on tracking them and predicting their impact on marine life.

But a bigger question is why the plumes formed at all. After all, anyone who's ever seen the sheen of oil on a puddle or shaken a bottle of salad dressing knows that oil floats.

"Oil and water don't naturally mix," said Richard McLaughlin,