The Kilbrannan Sound is a large arm of the Firth, separating the Kintyre Peninsula from the Isle of Arran.

Off Greenock, an anchorage, known as the Tail of the Bank narrows the estuary of the River Clyde to 2 miles (3.2 km) wide.

[14][15] The Irish Sea and the Firth of Clyde's southerly boundary, as defined by the Scottish Government, is between the southern tip of the Kintyre Peninsula and Corsewall Point on the Rhins of Galloway.

[16][17] The Highland Boundary Fault enters the Firth off the east coast of Kintyre Peninsula in the south.

The fault crosses the south eastern tip of the Cowal Peninsula at Toward Point, where it can be seen on the surface by the presence of Old Red Sandstone.

[25]Western Ferries, is a Private Limited Company,[26] it operates the service between Hunters Quay and McInroy's Point near to Gourock.

[33] There are lighthouses at: There are navigation beacons at: The Field Studies Council has a marine research station, based in Millport, on the island of Great Cumbrae.

(Coordinates: 55°56'32"N 04°36'32"W)[54][3][55] In September 2008, Scotland's first No Take Zone (NTZ) was introduced in Lamlash Bay, on the Isle of Arran.

Maerl is a slow-growing coral-like calcareous red algae (it grows only 1 mm per year) and is an important Scottish species.

Studies show that both scallop dredging and organic waste from fish farms, significantly impact Maerl.

[56][5] In 2014, 71,200 hectares (712 km2) at the south of the Firth between Kintyre Peninsula and the Rhins of Galloway, on the North Channel boundary.

This is a rich environment for plankton, which provide food for fish, that are in turn eaten by higher marine predators and seabirds.

On the lower Clyde, only one shipyard still operates, Ferguson Marine, which is located next to Newark Castle, Port Glasgow.

The remains of former sites of shipyards on the Clyde are being redeveloped into areas that contain residential housing, leisure facilities, and commercial buildings.

For example, the Battle of Largs, which was fought on the Firth, in 1263, was a geopolitical turning point: it marked the end of Norse ambitions in Britain.

[117] Beginning in the 16th century, the Firth increasingly became a conduit for commercial and industrial products, including: herring; timber; wine; sugar; tobacco; textiles; iron and steel; coal; oil; industrial chemicals; distillation and brewing; ships, locomotives, and other vehicles; and other manufactured products.

The area became famous worldwide for its significant contribution to yachting and yachtbuilding with notable designers including: William Fife III; Alfred Mylne; G L Watson; David Boyd.

The "lower Clyde" shipyards of Greenock and Port Glasgow, most notably Scott Lithgow, played an important historical role in shipbuilding.

Well into the 20th century, a large proportion of the world's ship construction took place around the upper Firth and River Clyde.

Many towns, such as Gourock, Largs, Ayr, Dunoon, Rothesay, flourished during this period and became fully fledged resorts with well-appointed hotels and attractions.

The steam-powered PS Waverley—in addition to its regular service—still makes cruising trips to the coastal towns that have been popular tourist destinations since the 19th century.

There is frequent rail service to and from the Clyde coast, including links to Oban and Fort William, with city terminals in Glasgow and Edinburgh.

[68] In Greenock, the large dry dock and ship-repair facilities at Inchgreen opened in 1964, and were subsequently taken over by Scott Lithgow.

Submarine Squadron 14 or SUBRON14, also known as Site one, Holy Loch was in operation between 1 July 1958, up until the end of the Cold War.

In 1942, a underwater oil pipeline was laid across the Firth, Operation Pluto, the world's first deep-water test of this technology.

[125] During both World wars, the Cloch Point To Dunoon Anti-submarine Boom was in place to protect the upper Firth.

Including the former sites of shipyards; Hunterston B nuclear power station; Inverkip power station; ExxonMobil fuel oil terminal site at Bowling; Nobel explosives plant at Ardeer and the Hunterston Ore Terminal.

Whilst the reason for this mild climate is the subject of debate[135] it is historically considered to be due to the moderating influence of the North Atlantic Drift, a warm oceanic current that is the eastern extension of the Gulf Stream[136] which originates in the tropical waters of the Gulf of Mexico.

Plastic debris may result in entanglement and ingestion by aquatic life such as birds, fish and marine mammals, causing severe injury or death.

In severe cases, with effects on surrounding tourism or real estate value, the clogging of drains and other hydraulic infrastructure leading to increased flood risk and further pollution.