While borders traverse both land and sea, current research has mostly concentrated on issues concerning terrestrial borders. Simultaneously, a new body of scholarship has shown how the seemingly boundless oceans are in actuality subject to a variety of bordering forces. As such, we review current research on maritime borders in geography and other related disciplines in three categories: oceanic resource extraction and environmental conservation, volume geography and wet ontology, and concepts of ocean frontiers and voluminous states. Conclusively, we propose land-ocean inter-bordering, multiple materialities, and mobile state power as three future issues to respond to the rapid-changing maritime borders.