Firth locally the change is held to be at the Tail of the Bank where the river crosses a sandbar off Greenock at the junction to the Gare Loch, or even further west at Gourock point. However, some firths are exceptions. The Cromarty Firth on the east coast of Scotland, for example, resembles a large loch with only a relatively small outlet to the sea and the Solway Firth and the Moray Firth are more like extremely large bays. The Pentland Firth is a strait rather than a bay or an inlet. These are connected to, or form part of, the
Firth which are not termed such – Likewise, in the Northern Isles, the words "firth" and "sound" are often used arbitrarily or interchangeably. Bluemull Sound for example, is very similar to some of the firths in the Shetland Islands. Firth Firth is a word in the Scots and English languages used to denote various coastal waters in Scotland and even a strait. In the Northern Isles, it more usually refers to a smaller inlet. It is linguistically cognate to "fjord" (both from Proto-Germanic *"ferþuz") which has a more constrained sense in English. Bodies of water named "firths" tend to be more