Grain size data was analysed in sediment samples from the IODP core 375-U1526B in the Southwest Pacific. The core was drilled at 2888 m below sea level on the western flank of the Tūranganui Knoll Seamount, along the Hikurangi Subduction Margin, offshore the North Island of New Zealand. The core was analysed over 0.04-26.16 m (CSF-A), dated from 1-1304 ka, in total 154 samples were analysed. A Mastersizer 3000, Malvern Instrument Inc was used to analysed the sediment, then the analysed grain-size data was processed by Gradistat v 9 based on the Folk and Ward Method. Sortable silt was calculated for every sample for bottom water velocity reconstruction.