Here we report on the "scrolling" of planar graphene induced by water as a result of the interplay between water capillarity and graphene elasticity. This scrolling leads to the formation of stable nanochannels that encapsulate water and nanoscale objects. We demonstrate that these graphene nanochannels can be used as nanofluidic platforms for dynamic imaging of nanoscale processes in liquids with Transmission Electron Microscopes (TEMs). These water-impermeable graphene nanochannels have practical application in the design of nanofluidic devices used in biosensors and many analytical separation devices.