sentences:  Under the Treaty of Plussa, Russia lost Narva and the southern coast of the Gulf of Finland, being its only access to the Baltic Sea.The situation was partially reversed 12 years later, according to the Treaty of Tyavzino which concluded a new war between Sweden and Russia.Sweden's defeat in the Great Northern War in 1721 resulted the Treaty of Nystad, the Russian Empire gained Sweden's Baltic territories Estonia (nowadays northern Estonia) and Livonia, (nowadays southern Estonia and northern Latvia).