This field activity may be implemented during late winter or early spring when things have not quite thawed. From a frozen pond, students collect bathymetric data, measure water temperature and conductivity, locate ground-water inputs, and extract a sediment core. Back in the lab, they make hand and computer-contoured bathymetric maps, temperature and conductivity cross-sections, and run visual-core log, loss-on-ignition, and magnetic susceptibility tests. Then they draw conclusions about water movement in the pond, pond-water residence time, and the pond's depositional and hydrologic history. This activity is designed for upper-level undergraduate and graduate-level geohydrology courses. Learning goals, context for use, teaching tips, materials, assessment tips and related resources are provided.