Firth

Firth is a word in the English and Scots languages used to denote various coastal waters in the United Kingdom, predominantly within Scotland.

It is linguistically cognate to Scandinavian fjord and fjard (all from Proto-Germanic *ferþuz), with the original meaning of "sailable waterway".

A firth is generally the result of ice age glaciation and is very often associated with a large river, where erosion caused by the tidal effects of incoming sea water passing upriver has widened the riverbed into an estuary.

In navigation terms, the dredged River Clyde Channel for shipping meets the Firth of Clyde Channel at the Tail of the Bank, where the river crosses a sandbar off Greenock as the estuary widens at the junction to the Gare Loch.

In Shetland in particular, "firth" can refer to smaller inlets, although geo, voe and wick are as common.

The Firth of Lorn and other nearby waterways
The estuary of the River Nith , opening into Solway Firth south of Dumfries .
Entrance to the Cromarty Firth , with oil rigs behind
Dundee from the Fife shore of the Firth of Tay
Map of the Pentland Firth and associated lands
Cliffs in Saviskaill Bay on Rousay , looking northward to Westray across Westray Firth
Loch Eriboll
The Firth of Thames is the large bay to the southeast