Glaciers in the Arctic and Antarctic have been losing ice at an increasing rate over the last several decades, leading to an acceleration in global sea level rise. Much of this increase has occurred in concert with warming of the ocean water in contact with glaciers at ice sheet margins. However, our understanding and ability to predict these changes is limited by the complex range of processes occurring at glacier-ocean interfaces. In this talk, I will discuss our recent and ongoing efforts to understand and model three of these problems: intrusion of seawater beneath glaciers, turbulent heat entrainment in the ice-water boundary layer, and the mechanical interaction of icebergs with the glacier front. I will conclude by explaining the implications of these small-scale problems for the highly consequential problem of predicting future sea level rise.