The 2004 Indian Ocean tsunami transported large boulders shoreward at Pakarang Cape, Thailand. To elucidate boulder transport processes using their original locations, initial tsunami waveform, and coastal profiles, we conducted a cross-sectional calculation. Our results indicate that the tsunami (trough arrives first) might have displaced boulders and cast some on the tidal bench. However, if the wave crest arrives first, only some reef-edge boulders are displaced and emplaced on the tidal bench. More and larger boulders are displaced and deposited on the tidal bench when the reef slope is gentle, as at Pakarang Cape, than for a steep slope case.