How deep is the firth of Clyde?

The Firth of Clyde is a fjord on the west coast of Scotland, formed by the drowning of the valley of the River Clyde and its tributaries when the sea level rose at the end of the last ice age. The firth is about 100 km (62 mi) long and 40 km (25 mi) wide, with a maximum depth of 200 m (656 ft) in the Kyles of Bute. The firth is important for shipping, fishing, and tourism, and is home to several large cities, including Glasgow, Greenock, and Ardrossan.