Following the 2018 eruption of Kīlauea Volcano (Neal and others, 2019) and the subsequent collapse of the Halema’uma’u crater, groundwater gradually seeped into the newly-deepened crater (Nadeau and others, 2020). Water was first observed in the crater on 7/26/19, and the water level increased over time until 12/20/20, when the crater again filled with lava, vaporizing the lake. In the intervening time, three sets of water samples were collected by unoccupied aircraft systems (UAS) and analyzed for water chemistry, water isotopes, and sulfur isotopes. The solids filtered from the collected water samples were analyzed by XRD and SEM, as well as digested and analyzed for their chemical composition. Additionally, two flights with a multirotor UAS instrumented with a miniature multi-GAS (multiple Gas Analyzer System) instrument were completed on October 26, 2019. During these flights, gas plume compositions within Halema’uma’u crater were measured. References Nadeau, P., Diefenbach, A.K., Hurwitz, S. and Donald, A., 2020. From lava to water: a new era at Kīlauea. Eos, doi:10.1029/2020EO149557. Neal, C.A., Brantley, S.R., Antolik, L., Babb, J.L., Burgess, M., Calles, K., Cappos, M., Chang, J.C., Conway, S., Desmither, L. and Dotray, P., 2019. The 2018 rift eruption and summit collapse of Kīlauea Volcano. Science, 363, 367-374.