We report on hydrographic profiles and timeseries data from within the Ross Ice Shelf Cavity.  The Aotearoa New Zealand Ross Ice Shelf Programme HWD2 borehole through the central region of the Ross Ice Shelf in December 2017 enabled a telemetered hydrographic mooring to be deployed.  Located 300 km from the ice shelf front beneath 320 m of ice, with a water column around 400 m deep, the initial thermohaline profile data over a ten-day period showed significant mid-water column variability.  On-going telemetered data support the view of the structure being a well-defined basal boundary-layer separated from the deep inflowing high salinity shelf water (HSSW) by a highly interleaved mid-water-column region.  The nature of this interleaved region is critical for understanding vertical exchange and its influence on cavity circulation.  The profiled data shows identifiable overturns that are likely short-lived.  The new results show a continuous range of timescales for thermohaline variability up to around ~one month intervals.  In addition, there are some remarkable transients – several exceeding 0.1°C change in only a few hours. We speculate on how this degree of variability could exist so far from the open ocean, and consider the possibility it is related to distant tidally-induced mixing generating thermohaline intrusions.  This has significant implications for circulation and mixing of warm inflowing water and for the future of the ice shelf in a warming worl.