ONTARIO, LAKE, the smallest and most E. of the five great lakes of North America, in the St. Lawrence basin, partly belonging to Canada and partly to the State of New York. It is an elon gated, oval shape, 172 miles in length, by a maximum breadth (in the center) of 60 miles; covering an area of about 5,400 square miles. Its surface level is about 334 feet below that of Lake Erie, and 231 feet above the tide level of the St. Lawrence. Its depth is said to average 490 feet; but in some places it is upwards of 600 feet in depth, and it is navigable throughout its whole extent for vessels 6f the largest size. The St. Lawrence (un der the name of the Niagara river) enters it near its S. W. and leaves it at its N. E. extremity, where it is much encumbered with small islands. Lake Ontario has many good harbors; and as it never freezes, except at the sides, where the water is shallow, its naviga tion is not interrupted like that of Lake Erie. It is, however, subject to violent
storms and heavy swells. Toronto, Kingston, Newcastle, and Niagara are the principal towns on the British side; and Oswego, Genesee, and Sackett's Har bor on the American bank. This lake re ceives numerous rivers, including the Trent and Humber on its N., and the Black, Genesee, and Oswego from its S. shores. It communicates by the Genesee river and Oswego canal with the Erie canal, and, consequently, with the Hud son river and New York City; the Niagara river and the Welland canal, at its S. W. extremity, unite it with Lake Erie, and the Rideau canal connects it with the Ottawa at Ottawa city. Nu merous sailing vessels and steamers of large size navigate this lake, which is the center of an extensive commerce.