Capacity to survive the oxygen deprivation depends on a number of developmental, morphological, and metabolic adaptations in plants. Imposition of hypoxia (deficiency of oxygen) accelerates growth of shoot axial organs and stimulates formation of adventitious roots and aerenchyma in tolerant plant species. As a result, the shoot actively transports oxygen to a flooded root. Simultaneous shifts occur in the metabolism, which are particularly severe under anoxia (total absence of oxygen). A majority of these morphological and metabolic adaptations are strictly regulated by plant hormonal system. Ethylene and gibberellins control enhanced growth, leading to the emergence of shoots of tolerant plants under flooding conditions. Recent findings show Sub1 gene which is important to submergence tolerance in rice to be linked with ethylene and gibberellin signaling. Ethylene is also involved in formation of aerenchyma in oxygen-depleted environment. Auxin regulates adventitious rooting and petiole elongation. Abscisic acid inhibits growth but stimulates metabolic adaptations by induction of anaerobic stress protein gene expression. Complete flooding and particularly total anoxia block ethylene production. Application of exogenous ABA, auxin, and some other growth regulators improves plant survival during oxygen deficiency. Complicated crosstalk between phytohormones under oxygen depletion is discussed as a milestone of plant adaptation.