The exchange of water between coral reef lagoons and the open ocean depends on the interplay between waves, buoyancy, wind stress, and alongshore currents. Some processes act to retain lagoon water such as onshore flows driven by surface waves, while others (e.g., the momentum jet that exits the lagoon) export lagoon water. To explore the impact of surface waves on the exchange dynamics, observations were made in Paopao Bay, French Polynesia, a nearly tideless coral reef lagoon system. The system has a typical barrier reef geometry with a shallow backreef, deep lagoon, and narrow pass connecting the lagoon to the ocean. Releases of surface GPS drifters were made concurrently with a two month deployment of moored instruments measuring waves, mean currents and offshore circulation. The drifter data were used to compute directional dispersion coefficients and to isolate the relative contributions of Eulerian, Lagrangian, and Stokes drift currents. The results indicate that interaction between the waves and lateral shear in the alongshore current contribute most to the dispersion. Wave dynamics are also important in determining the offshore extent of “new” ocean water sources to the lagoon.