On the 15 January 2022, the volcano Hunga Tonga–Hunga Ha'apai in the southwest Pacific Ocean (20°32'32.37"S 175°23'38.67"W) erupted in what proved to be the most powerful such event since Krakatau in 1883. Among the many impacts of the eruption, a substantial tsunami propagated throughout the southwest Pacific Ocean. The signatures of the eruption were recorded at a wide range of recording stations globally including the atmospheric pressure wave, the tsunami itself and in addition, higher order responses such as a tsunami associated with the pressure wave. Here we describe what is likely the most southerly oceanic measurement of the tsunami arrival as the event was detected in a sub-ice mooring at the grounding line of the Ross Ice Shelf at 82.47 o South. It was recorded on the margin of the Ross Ice Shelf along the Siple Coast at the KIS2 (Kamb Ice Stream 2) field camp by instruments deployed to record ice-ocean interactions in order to improve understand ocean effects on ice sheet stability.

The data were recorded at the Kamb Ice Stream KIS2 camp (Latitude -82.470442; Longitude -152.291643°). The channel is around 6 km long, 250 m high and 150 m wide beneath 410 m of ice and snow. In early 2022 a hot water borehole was drilled through the ice shelf to access the ocean. Hydrographic instruments were suspended in the ocean cavity late on the 11^th of January 2022 local time and four days later and 7,000 km to the north, the Hunga Tonga–Hunga Ha'apai eruption occurred.

At the instrument location the ice underside was at a pressure of 409 dbar and the sea floor was at 650 dbar. The instruments providing the data were three RBR Concerto CTDs (conductivity temperature depth instruments).  These instruments included a pressure sensor rated to 1000 (dbar) with an initial accuracy of ±0.05% full scale and a resolution <0.001% full scale so 1 cm. Sampling was at 1 minute intervals and sensor response time is <0.01s. The three instruments were at pressures of 425, 495 and 648 dbar respectively and all three gave consistent readings.