Students learn science best with activities that mirror the way scientists work. This article describes how geologists investigate groundwater flow systems in areas of karst topography--geologic formations shaped by dissolving bedrock--and provides a way for students to replicate this research. Students also use electric current to model water currents and map unseen flow routes. The study of groundwater flow routes also provides an excellent opportunity to demonstrate real-life applications of the types of inquiries scientists conduct every day. High school science students should readily identify with the struggles and satisfaction of investigating these unseen water paths in both field and lab activities. (Contains 5 figures and 5 online resources.)