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 of Clyde Common and grey seals abound in the firth. Harbour porpoises are also common and while dolphins are much less so, they have been spotted in the upper reaches of the firth in the summer of 2005. Whales do not favour the Clyde and although there have been instances of larger whales beaching themselves or becoming stranded in the upper firth, only smaller pilot or minke whales seem to visit with any kind of regularity. In 2005 the firth was listed as having the 2nd highest incidence of basking shark sightings in Scotland (after The Minch). In particular these huge sharks