The waterways of Canada available for steam navigation are on a magnificent scale. The main system extends from the mouth of the St. Lawrence at Belle Isle to Fort William and the head of Lake Superior—a distance of nearly 2,384 miles, and rendered navigable without interruption by a series of ship canals. Proceeding four hundred miles farther west, another long stretch of inland navigation begins with Lake Winnipeg, 240 miles long, into which, at its northern extremity, flows the mighty Saskatchewan, navigable for steamers one thousand miles! Not to mention smaller streams, the rivers St. John and Miramichi, in the Province of New Brunswick, afford 300 miles of navigable water and float a large amount of shipping. Ships of the largest size can ascend the Saguenay seventy-five miles. The Ottawa in its several reaches is navigable by steam for three or four hundred miles. Steamers ply on the Assiniboine, 250 or 300 miles westward from Winnipeg. The Mackenzie River is navigable for a thousand miles. The Fraser, the Thompson, and the Columbia rivers in British Columbia contribute largely to the steam tonnage of the Dominion. The Great Lakes,[38] commonly so called, are in reality great inland fresh water seas, often swept by gales of wind and combing billows, and sometimes, alas, strewed with wrecks. They have their breakwaters, lighthouses and steam fog-signals as fully equipped as similar oceanic structures and appliances. The Lake of the Woods and Lake Manitoba are each 100 miles long.