We report on the first measurements of fluid permeability in Antarctic pack ice, as well as the first direct measurements of the vertical conductivity of extracted sea-ice cores. These measurements were taken during the Australian Sea Ice Physics and Ecosystem Experiment (SIPEX) in September–October 2007. We find that the granular sea ice prevalent in the Antarctic apparently exhibits a percolation threshold for fluid flow at a brine volume fraction of about 10%, which is higher than the 5% seen in columnar sea ice. Nevertheless, the universal exponent of 2 from lattice percolation theory still closely captures the critical behavior of the permeability near the threshold. In what we believe are the first observations of critical behavior in the electrical properties of sea ice, our conductivity data also display a percolation threshold. Moreover, we find remarkably close agreement between these data and the predictions of percolation theory with the universal critical exponent of 2. In our analysis we exploit theoretical relations which couple fluid and electrical properties.