Conversion of coastal sand dunes to plantations has intensified dramatically after the tsunami of December 2004, driven largely by the belief that bio-shields mitigated tsunami inundation. This assumption was tested using field-based mapping and remote sensing. A regression between the Normalized Difference Vegetation Index and inundation distance was non-significant, questioning the premise for large-scale bio-shield plantations, mostly Casuarina equisetifolia, an exotic timber with unquantified ecological impacts.