Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world, which results in huge economic loss. Approximately one-fourth of the global rice crops (approximately 40 million hectares) are grown in rainfed lowland plots that are prone to seasonal flooding. A great progress has been made during last two decades in our understanding of the mechanisms involved in adaptation and tolerance to flooding/submergence in rice. In this review, we summarized the physiological and molecular mechanisms that contribute to tolerance of flooding/submergence in rice. We also covered various features of flooding stress with special reference to rice plants, viz. different types of flooding stress, environmental characterisation of flood water, impact of flooding stress on rice plant and their morphological, physiological and metabolic responses under flooding. A brief discussion on the tolerance mechanism in rice exhibited to different types of flooding will be focused for the future crop improvement programme for development of flooding tolerant rice variety.