The erosion problem along Playá Union presents significant challenges for future port expansion at Puerto Rawson. This research seeks to address the question of how to achieve a sustainable and durable port expansion, while minimizing environmental impacts, particularly concerning sediment imbalance along the coastline? Using 30 years of wave data, both normal and extreme wave conditions are simulated with SWAN, a numerical based wave model. Conceptual port expansion designs are developed, resulting in a final design with an integrated fully dimensioned breakwater. Based on visual inspections, data, and research, a new cement mixture is proposed for the breakwater armour units. A Life Cycle Assessment evaluates the environmental impact, while the effect on alongshore sediment transport is assessed using the SWAN model outcomes and the CERC formula. Visual inspection of the current breakwaters lead to a 6.3% reduction in material use in the new breakwater through reuse of armour units. Furthermore, the proposed cement mixture integrates porphyry quarry waste as the coarse aggregate, a choice also supported by prior research in sustainability. With the new End-of-Life approaches added, the total shadow costs are reduced by 22%. The hydrodynamical analysis and model result in extreme wave heights up to 3.98 m at the toe of the breakwater. By applying a neural network and a k-means algorithm on the wave data, five regular wave conditions are run in the SWAN model. The alongshore sediment transport is impacted by new breakwater concepts. Relying solely on the breakwater layout to counteract erosion north of the port, however, does not prove to be a viable approach. Based on design criteria and aspirations, the final conceptual design proposes the removal of the existing southern breakwater, while retaining sufficient space for future port expansion. The breakwater, integrated in the final design, is dimensioned based on standard design principles. To conclude, the data and model provide valuable insights into the coastal dynamics around Puerto Rawson. The proposed concrete mixture, along with the End-of-Life solutions, minimize environmental impact and enhance durability of the armour units. The sustainable breakwater design, effectively integrated into Puerto Rawson, accommodates for future port expansions