They are believed to be the result of marine erosion at a time when sea levels were higher than at present, probably during a late interglacial period.

[3] The nature of the seabed in the firth has been studied by several methods, including echo-sounding, sampling with grabs, and surveys using submersible vessels.

When the west-going flood tide emerges into the main part of the firth it can form overfalls, dangerous breaking steep seas, particularly if it meets a swell from the west or south-west.

The varied conditions, with some areas exposed to strong currents and others sheltered, and the range of depths found in the firth contributes to the great diversity of its habitats.

Species of particular interest are the sea fan Swiftia pallida and its associated anemone Amphianthus dohrnii[6]: 20  The whole of the Firth of Lorn became a Marine Protected Area in 2014.

[7] Marine tourism is important to the area, and includes scuba diving, sea angling, wildlife watching, sailing, and commercial boat tours.

[9] The Firth of Lorne featured as the location for the boat chase near the end of the second James Bond film From Russia with Love, released in 1963.

Also the islands of Easdale, Seil and Cuan sound all feature in Florence + the machines video, Queen of peace and long and lost.