Every year over 100 fatalities occur in the United States in the surf zone along our beaches. Rip currents account for the majority of surf zone fatalities with high surf, sneaker waves, longshore currents and others contributing. A first step in predicting rip currents is understanding how, when, and where they form. This lesson provides insight into how nearshore circulation, wave dynamics, and bathymetry are involved in rip current formation. Topics covered in this module include: nearshore terminology, circulation and waves, rip current classification and characteristics, and rip current forcing mechanisms. This module is the second of three modules covering the forecasting of rip currents. It was updated in 2020 to address recent advances in rip current research.