How did Peter the Great gain territory for Russia along the Baltic Sea?

Peter the Great gained territory for Russia along the Baltic Sea primarily through military conflict and strategic diplomacy. He fought the Great Northern War (1700-1721) against Sweden, which was a dominant power in the region. After several key victories, particularly the Battle of Poltava in 1709, Russia secured significant territorial gains through the Treaty of Nystad in 1721, establishing St. Petersburg as a major port and capital. This expansion helped Russia access important maritime trade routes and assert its influence in Northern Europe.