Answer:
First the water which is present in the sea and ocean evaporated in the process of evaporation due to the radiation of sunlight which changes liquid into vapours. These vapours goes to the atmosphere and forms cloud. These clouds moves to the hilly areas by winds and falls in the form of rainfall and snowfall. The water which is present in these hilly areas starts melting due to increase in temperature and this water flows down the land through streams and again meets the ocean.