日露和親条約
In 1852-54, Posyet followed Admiral Yevfimy Putyatin on the frigate "Pallas" to Japan. Accompanied by novelist Ivan Goncharov and inventor Alexander Mozhaisky, Posyet explored and mapped the northern coastline of the Sea of Japan, including Possiet Bay, which now bears his name. In 1856 he carried to Japan the news of the ratification of the Treaty of Shimoda. Posyet's journeys and published observations made him something of an expert on Japan. Years later, he negotiated with Enomoto Takeaki the Treaty of Saint Petersburg, which brought entire Sakhalin Island into the Russian fold.