We present previously unpublished results and summarize recent computer simulation studies of the interfaces between water or aqueous solutions and liquid or solid mercury which serve as realistic molecular-level models of the electrochemical interface. Most simulations were performed employing a simple rigid crystal model of mercury. It is first shown that the water structure is not strongly affected by using a more realistic liquid model, thus justifying the simpler approach. Structural, dynamic and thermodynamic properties near the rigid mercury crystal are calculated for Li+, F- and I- ions dissolved in water. The differences between the ions are rationalized on the basis of solvation and steric interactions.