Steady-state numerical groundwater-flow models were constructed for the islands of Kaua'i, O'ahu, and Maui, Hawai'i. Separate models were created for each island using MODFLOW-2005 (Harbaugh, 2005) with the Seawater Intrusion (SWI2) package (Bakker and others, 2013), which allows simulation of freshwater and saltwater in ocean-island aquifers. The purpose of the models is to enable quantification of the hydrologic effects of withdrawals and changes in climate. These effects include water-table depression, saltwater rise, and reduction of natural groundwater discharge to streams, springs, and the ocean. The effects can place limits on groundwater availability. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20205126).