Coral reefs are widely recognized as effective dissipaters of wave energy. Spurs and grooves (SAG) are common features of fore reefs worldwide and are thought to be particularly efficient at dissipating wave energy. However, very few studies have collected in-situ hydrodynamic data to verify this and understand SAG interactions with hydrodynamic forces. We present in-situ wave data from contrasting SAG sites at Moorea, French Polynesia and One Tree Reef in the southern Great Barrier Reef, Australia. We measured extremely high rates of wave energy dissipation (up to 0.1 kW/m) than the adjacent spur (mean =0.01 kW/m²). Correlations between measured dissipation, wave height and depth allowed us to develop a conceptual model showing that SAGs dissipate more energy under high wave conditions at low tides, while the reef crest dissipates more energy at high tides under small wave conditions. Further study is required to better understand and model the hydrodynamics of SAG zones and the important role they play in reef dynamics and coastal protection.