Loch Fyne (Scottish Gaelic: Loch Fìne, meaning Loch of the Vine or Wine, is a sea loch on the west coast of Argyll and Bute, Scotland. It extends 65 kilometres (40 mi) inland from the Sound of Bute, making it the longest of the sea lochs. It is connected to the Sound of Jura by the Crinan Canal. Although there is no evidence that grapes have grown there, the title is probably honorific, indicating that the River, 'Abhainn Fìne', was a well-respected river.
Loch Fyne has a reputation for its oyster fishery, and as a consequence the loch has given its name to the locally-owned Loch Fyne Oysters and to the associated Loch Fyne Restaurants. It is also notable for its herring-fishing industry, and hence the famous Loch Fyne Kipper, originally caught using the drift-net method. In the mid-19th century, Loch Fyne was the centre of the battle between the traditional drift-net fishermen and the new trawl-net fishermen who sprang up around Tarbert and Campbeltown in 1833.
Loch Fyne is a popular area for sport diving and fishing. It is also a popular tourist destination with attractions such as Inveraray Castle and the nearby ruins of Castle MacEwen.
The village of Portavadie is on the east shore of the loch. A passenger ferry traverses the loch to Tarbert from the slipway at Portavadie.
Dolphins, seals and otters inhabit the loch, and basking sharks can appear in its waters during the summer months. A Ross's Gull was present at the loch in early 2007.
In the north the terrain is mountainous, with the Arrochar Alps, Beinn Bhuidhe, Glen Shira, Glen Fyne, Glen Croe, Arrochar, Tyndrum and Loch Lomond nearby.
Around a quarter of a million troops trained at HMS Quebec, No.1 Combined Training Centre, Inveraray in amphibious-landing techniques on the shores of Loch Fyne prior to the D-day landings.