The morphodynamic of Tunquen beach, distal zone of Algarrobo headland bay, central Chile, and its relationship with both, the relative shoreline changes in the mid-term scale and pocket beach conditions, are presented. Tunquen is an intermediate high-energy beach, with transverse bar and rip. A rhythmic topography produced by equidistant megacusps is associated to swash circulations patterns (horn divergent). Sediments correspond to a well classified medium to coarse sand. During the last 45 years, the relative position of the shoreline has shown small variability (+/- 50 m). This embayment presents stable conditions associated to the shoreline changes and the determined beach type.