Oil and water don’t mix. The interface between the two liquids is a building block of the most widely used industrial process to purify chemicals in energy production (from nuclear energy to biofuels) and storage (batteries). A recent discovery may unlock mechanisms that transport molecules across the boundary between oil and water. Simulations and analyses reveal a highly diverse and dynamic structure at the interface. In fact, the crests of tiny waves of water into the oil phase cause water to behave as if it is a gas—potentially easing transport of chemicals from water to oil.