<P> At Little Falls and The Noses, the Mohawk breaks through mountain barriers in a deep, rocky ravine; and at Cohoes, about 1 mile (1.6 km) from its mouth, it flows down a perpendicular precipice of 70 feet (21 m). Below Troy the tributaries of the Hudson are all comparatively small streams . South of the highlands the river spreads out into a wide expanse known as Haverstraw Bay . A few small streams upon the extreme eastern border of the state flow eastward into the Housatonic River, and several small branches of the Passaic River rise in the southern part of Rockland County . </P> <P> Lake Erie forms a portion of the western boundary of the state . It is 240 miles (390 km) long, with an average width of 38 miles (61 km), and it lies mostly west of the bounds of the state . It is 334 feet (102 m) above Lake Ontario, 565 feet (172 m) above sea level, and has an average depth of 120 feet (37 m). The greatest depth ever obtained by soundings is 270 feet (82 m). The harbors upon the lake are Buffalo, Silver Creek, Dunkirk, and Barcelona . </P> <P> The Niagara River, forming the outlet of Lake Erie, is 34 miles (55 km) long, and, on average, more than a mile wide . About 20 miles (32 km) below Lake Erie the rapids commence; and 2 miles (3.2 km) further below are Niagara Falls . For 7 miles (11 km) below the falls the river has a rapid course between perpendicular, rocky banks, 200 to 300 feet (61 to 91 m) high, but below it emerges from the highlands and flows 7 miles (11 km) to Lake Ontario in a broad, deep, and majestic current . </P> <P> Lake Ontario forms a part of the northern boundary to the western half of the state . Its greatest length is 130 miles (210 km) and its greatest width is 55 miles (89 km). It is 232 feet (71 m) above sea level, and its greatest depth is 600 feet (180 m). Its principal harbors on the American shore are Lewiston, Youngstown, Port Genesee, Sodus and Little Sodus bays, Oswego, Sackets Harbor, and Cape Vincent . The St. Lawrence River forms the outlet of the lake and the northern boundary of the state to the east line of St. Lawrence County . It is a broad, deep river, flowing with a strong yet sluggish current until it passes the limits of this state . In the upper part of its course it encloses a great number of small islands, known as the Thousand Islands . </P>

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