The first phase of the SALSA Project involved a 100-mile traverse to subglacial Lake Mercer to deliver drilling equipment and establish a safe route. This route requires traveling through a shear zone, where movement of two glaciers causes cracks in the ice. These cracks are called crevasses and can be dangerous to the crew. The crew uses ground-penetrating radar (GPR) to navigate safely through the shear zone. This lesson explores what GPR is, how it works, how the SALSA crew uses it, and how similar radar technology could be used to explore other areas as well.