Results of study of natural waters of the Baidar valley (southwestern Crimean Peninsula) obtained during the 2018-2019 field works are presented. Major groundwater resources of the study area are confined to the Upper Jurassic aquifer complex, which serves as a recharge source for the aquifer systems of the Plain Crimean and the Azov-Kuban' artesian basins and hydrogeologic folded region of the Crimean Mountains mega-anticlinorium. The regional waters are fresh and ultrafresh, predominantly of calcium bicarbonate composition, with TDS varying from 208 to 1269 mg/dm3. The study enabled their classification into eight geochemical groups: (1) waters of a regional fracture zone in carbonate-terrigenous rocks affected by continental salinization; (2) waters of a regional fracture zone affected by leaching of aluminosilicates and sulfide oxidation; (3) waters of a regional fracture zone dominated by sodium aluminosilicates in the fracture filling (long-term interaction in the water-rock system), affected by continental salinization; (4) regional fracture zones dominated by sodium aluminosilicates affected by anthropogenic continental salinization; (5) groundwaters in fracture-vein aquifers affected by leaching of aluminosilicates and sulfide oxidation; (6) fracture-vein aquifers affected by leaching of sodium aluminosilicates (long-term interaction in the water-rock system); (7) waters in fractured karst aquifers; and (8) surface waters subjected to continental salinization.