an island belonging to Russia, stretches across the mouth of the Gulf of Riga, between N. Lat. 58. and 58. 40., E. Long. 21. 40. and 23. 20. Its length from S. by W. to N. by E. is about 45 miles; average breadth, 12 miles; area, about 1200 square miles. Next to Zealand, this is the largest of the islands in the Baltic. It has steep and bold coasts, and a rocky undulating surface, watered by numerous streams. The rocks are for the most part calcareous; and the soil, though not naturally fertile, may be made productive by means of manure. A great part of the island is covered with forests, and a considerable extent of it is used as pasture ground. The climate is milder in winter than that of the adjacent mainland; but in spring and autumn severe storms frequently occur. Corn is raised in sufficient quantities to furnish an article of exportation; wheat, rye, barley, and oats being the principal crops; while hemp and flax are also cultivated. Many of the inhabitants are also employed in pastoral and piscatorial pursuits. Few manufactures are carried on. The majority of the people are Lutherans; and the chief town is Arensburg, on the S.E. coast. Oesel at one time belonged to the Teutonic knights, but was seized by the Danes at an early period, and ceded by them to Sweden in 1645. In the beginning of the eighteenth century it was taken possession of by Russia, to which power it was finally ceded in 1721 along with Livonia, of which government it forms a part. Pop. about 40,000.