The high activities of 222Rn and low activities ratios of 228Ra/226Ra in the bottom water of Chinhae Bay suggested that the submarine groundwater may discharge to the overlying water. Therefore, nutrient budgets are required to assess the contribution by the submarine groundwater discharge in the biogeochemical processes of Chinhae Bay. Regardless of freshwater input by submarine groundwater discharge, recirculation of seawater through between sediment by tidal wave is also considered as a submarine groundwater and highly significant for nutrient supply in coastal ocean. Therefore, further studies using Ra mass balance are required to estimate more correct submarine groundwater discharge to Chinhae Bay.