A geochemical investigation (major cations and anions, stable isotopes of oxygen and hydrogen, pH, and salinity) was conducted to identify the sources of groundwater recharge to the surficial aquifer system in Everglades National Park. The weighted mean values of δ¹⁸O and δD of rainfall were −2.83‰ and −10.59‰, respectively. A mean deuterium excess value of 12 suggests that evaporation of Everglades surface water contributes between 7% and 12% to the local precipitation. Most shallow groundwater in the surficial aquifer system (<28 m) is recharged throughout the year by Everglades surface water and or canal water exposed to evaporation....