Coastal erosion was reported since 2000 in Tanjung Piai, a tourist destination at Peninsular Malaysia�s southernmost tip. Attempts to overcome the erosion neither offered a permanent solution nor were able to preserve the mangroves. Detached breakwaters were constructed to reduce wave energy and sustain the mangroves. A man-made island near the breakwaters was subsequently reclaimed. Problems arise when coastal structures are built without a full understanding of dynamic spatial, temporal and principles underlying sediment dynamics. The hydrodynamic impact of currents due to the breakwaters and island interaction was investigated via numerical modelling. The reclamation induces faster currents between the southernmost breakwater and the island with faster currents near the relatively deeper seabed fronting the breakwaters affecting navigation and sediment transport. Having less breakwaters and shifting the island further seaward from the breakwaters causes less hydrodynamic impact. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021.