An estuary on the east coast of Scotland at the mouth of the River Tay, the Firth of Tay extends eastwards from the confluence of the Rivers Earn and Tay, opening into the North Sea beyond Buddon Ness in Angus and Tentsmuir Point in Fife. Its channel is 23 miles (37 km) in length and although quite narrow, because of sandbanks, has a maximum width of 3 miles (5 km) at Invergowrie to the west of Dundee. The Firth of Tay is crossed by the Tay Road Bridge and Tay Railway Bridge at Dundee which is the principal port and settlement on the estuary.