Bohai Bay (or 渤海湾, 渤海灣) is one of the three bays forming the Bohai Gulf, the innermost gulf of the Yellow Sea, in northeast China. It borders Hebei province and Tianjin Municipality. The three bays are Laizhou Bay to the south, Liaodong Bay to the north, and Bohai Bay to the west. It is the most southerly sea in the northern hemisphere in which sea ice can form.
Zhang Jian is the only person to cross Bohai Bay with his 76.5-mile (123 km) wetsuit crossing in 2000 in 50 hours 22 minutes.