New concepts or chemistry is an urgent requirement for rechargeable batteries to achieve a low-cost, user-friendly nature with adequate energy densities and high levels of safety. Rechargeable seawater batteries (SWBs) are a new electrochemical system for the storage of electrical energy that utilizes seawater, as an infinite resource, as a source of the Na+ ion cathode. Seawater is a naturally available abundant renewable resource that covers nearly 70% of the Earth's surface. This review provides an essential comprehensive introduction to new rechargeable SWBs. First, we present details of seawater and then the history of primary SWBs and rechargeable SWBs, and the structure and chemistry of rechargeable SWBs. Next, we describe the research progress that has so far been made on various components of SWBs, such as cathode current collectors, electrocatalysts, solid electrolyte, anodes, and non-aqueous electrolyte, including the performance metrics reported in the literature. Moreover, some concepts of modified rechargeable SWB design for desalination and CO2 reduction application are discussed. Lastly, we provide our future outlook on the development of rechargeable SWBs and emphasize the main practical issues with the hope of stimulating further research progress.