This is the fourth module in our series on open water waves. As deep-water waves approach the coastline, they encounter shallower water and begin to interact with the sea floor while evolving into shallow water waves. This module uses an interactive wave calculator to look at a variety of shallow-water wave behaviors, including shoaling, refraction, reflection, breaking, attenuation, and coastal run-up and set-up. All are important considerations when forecasting for small craft and other recreational interests in the near-shore environment.