The Battle of Grengam (, . ) of 1720 was the last major naval battle in the Great Northern War that took place in the Åland Islands, in the Ledsund strait between the island communities of Föglö and Lemland. The battle marked the end of Russian and Swedish offensive naval operations in Baltic waters. The Russian fleet conducted one more raid on the Swedish coast in spring 1721, whereupon the Treaty of Nystad was signed, ending the war.