Аннотация:The results of studies of extreme floods in Crimean rivers in the summer of 2021 are presented. Analytical and historical generalization is made for the problem of the adverse effects of water and mud flows in Crimea, and the factors of flood and mudflow formation in Crimean rivers in 2021 are analyzed. The maximal water discharges and levels are evaluated, and the dynamics of flood wave propagation in the Bel’bek River basin is examined. The hazardous hydrological phenomena that have taken place are shown to be unique, and their adverse effects are evaluated.