Nanoscale transport of ions and liquids is crucial for many geological and biological processes, but also for the design of efficient membranes for desalination, filtration, or osmotic energy harvesting. While the most salient behaviors arise at the molecular scale, such ultimate confinement has so far been achieved on a limited number of geometrical designs restricted to specific materials. To bypass previous technological limitations, we investigated transport in molecular-thick water films that spontaneously form, whether onto fully wettable substrates surrounded by water vapor or thanks to stabilization with surfactants. In the first case, we observed that ion transport is hindered nearby silica within a molecular layer of ∼3Å, above which continuum models successfully capture our observations. In the second case, we show that new properties can arise from the film deformability. Collaborators: Aymeric Allemand, Changwoo Bae, Menghua Zhao, Olivier Vincent, Christophe Ybert, Laurent Joly.