The Peter the Great Gulf (Russian: Залив Петра Великого) is a gulf on the southern coast of Primorsky Krai, Russia, and the largest gulf of the Sea of Japan. The gulf extends for 185 km (115 mi) from the Russian-Chinese border at the mouth of the Tumen River in the west across to Cape Povorotny in the east, and its bays reach 90 km (56 mi) inland. Vladivostok, the largest city and capital of Primorsky Krai, and Nakhodka, the third largest city in the Krai, are located along the coast of the gulf.
The Peter the Great Gulf has a coastline of about 1,500 km (930 mi), with the largest bay of the gulf of about 6,000 km2 (2,300 sq mi) divided by the Muravyov-Amursky Peninsula and the Eugénie Archipelago into the major bays of Amur Bay to the west and the Ussuri Bay to the east. The coast is indented by many smaller minor bays, including Possiet Bay, the Zolotoy Rog (the "Golden Horn"), and Diomede Bay in the west, Lazurnaya Bay (the "Shamora", with its sand beaches) in the Muravyov-Amursky Peninsula, and Strelok, Vostok and Nakhodka Bay to the east. The functioning of these bays as harbours is severely limited by the freezing from early December to mid-April.
The Peter the Great Gulf contains numerous islands, including the Rimsky-Korsakov Archipelago and Furugelm Island to the west, and Askold Island and Putyatin Island to the east. The Eugénie Archipelago is separated from the Muravyov-Amursky Peninsula by the Eastern Bosphorus, which runs between Vladivostok and Russky Island, the largest island in the archipelago and Primorsky Krai. In 2012, Russky Island was connected to the mainland by the Russky Bridge.