In a field study in the Arctic, ejection of dense, saline plumes was observed 1 m below warm land-fast first-year sea ice, under conditions where the heat balance at the ice-ocean interface predicted melting. We describe the observed momentum, heat and salt fluxes in the boundary layer under the ice and the structure of the plume events. Measured downward salt flux was well correlated with upward oceanic heat flux. Our measurements indicate that turbulent heat forcing from below can play an important role for the desalination of warm and saline, hence permeable, sea ice.