Sydney Mines: town, Cape Breton Island, eastern Nova Scotia, Canada. It lies immediately northeast of North Sydney and faces Sydney across Sydney Harbor. Sydney Mines wasonce a major coal-producing community. Mining began locally in 1766, and in 1830 systematic operations were undertaken. One of the area mines extended about 5 miles (8 km) out under the sea. The last mine was closed in 1975. Inc. 1889. Pop. (1991) 7,551.

Sydney Mines is on the northern side of Sydney Harbor, near the mouth. It was earlier known as the Mines due to the coal mines abundant nearby. Although mining has been carried on since 1724, the first shaft for the General Mining Association in Sydney Mines was sunk in 1830. Manufacturing enterprises included corrugated steel culverts and the British Canadian Co-operative Society Limited, operating a dairy and a bakery.