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<p>Cave microclimate and geochemical monitoring is vitally important for correct interpretations of proxy time series from speleothems with regard to past climatic and environmental dynamics. We present results of a comprehensive cave-monitoring programme in Waipuna Cave in the North Island of New Zealand, a region that is strongly influenced by the Southern Westerlies and the El Niño–Southern Oscillation (ENSO). This study aims to characterise the response of the Waipuna Cave hydrological system to atmospheric circulation dynamics in the southwestern Pacific region in order to assure the quality of ongoing palaeo-environmental reconstructions from this cave.</p> <p>Drip water from 10 drip sites was collected at roughly monthly intervals for a period of ca. 3 years for isotopic (<span class="inline-formula"><i>δ</i>¹⁸O</span>, <span class="inline-formula"><i>δ</i>D</span>, d-excess parameter, <span class="inline-formula"><i>δ</i>¹⁷O</span>, and <span class="inline-formula">¹⁷O_excess</span>) and elemental (<span class="inline-formula">Mg∕Ca</span> and <span class="inline-formula">Sr∕Ca</span>) analysis. The monitoring included spot measurements of drip rates and cave air <span class="inline-formula">CO₂</span> concentration. Cave air temperature and drip rates were also continuously recorded by automatic loggers. These datasets were compared to surface air temperature, rainfall, and potential evaporation from nearby meteorological stations to test the degree of signal transfer and expression of surface environmental conditions in Waipuna Cave hydrochemistry.</p> <p>Based on the drip response dynamics to rainfall and other characteristics, we identified three types of discharge associated with hydrological routing in Waipuna Cave: (i) type 1 – diffuse flow, (ii) type 2 – fracture flow, and (iii) type 3 – combined flow. Drip water isotopes do not reflect seasonal variability but show higher values during severe drought. Drip water <span class="inline-formula"><i>δ</i>¹⁸O</span> values are characterised by small variability and reflect the mean isotopic signature of precipitation, testifying to rapid and thorough homogenisation in the epikarst. <span class="inline-formula">Mg∕Ca</span> and <span class="inline-formula">Sr∕Ca</span> ratios in drip waters are predominantly controlled by prior calcite precipitation (PCP). Prior calcite precipitation is strongest during austral summer (December–February), reflecting drier conditions and a lack of<span id="page3362"/> effective infiltration, and is weakest during the wet austral winter (July–September). The <span class="inline-formula">Sr∕Ca</span> ratio is particularly sensitive to ENSO conditions due to the interplay of congruent or incongruent host rock dissolution, which manifests itself in lower <span class="inline-formula">Sr∕Ca</span> in above-average warmer and wetter (La Niña-like) conditions. Our microclimatic observations at Waipuna Cave provide a valuable baseline for the rigorous interpretation of speleothem proxy records aiming at reconstructing the past expression of Pacific climate modes.</p>