Loch Sheil at Glen Finnan 25th May 1989

Loch Shiel (Scottish Gaelic: Loch Seile) is a 17 1⁄2 miles (28 km) long freshwater loch, 120 m (393 ft) deep, situated 12.4 miles west of Fort William in Lochaber, Highland, Scotland. Its nature changes considerably along its length, being deep and enclosed by mountains in the north east and shallow surrounded by bog and rough pasture in the south west, from which end the 4 km River Shiel drains to the sea in Loch Moidart near Castle Tioram.

Loch Shiel should not be confused with Glen Shiel, 40 km further north in Skye and Lochalsh, which contains a longer River Shiel and a much smaller Loch Shiel.

The surrounding mountains are picturesque but relatively rarely climbed as none quite reaches the 3,000 ft (910 m) required for Munro status. The area is well wooded compared to the many Highland areas that have suffered from overgrazing, and much of the shore is designated a Special Area of Conservation. Uniquely for a major loch[citation needed], the flow is not regulated. Boat trips for tourists have recently started on the loch.

Loch Shiel is only marginally above sea level and was in fact a sea loch a few thousand years ago when sea levels (relative to Scotland) were higher.
A ruined chapel can be found on the largest island said to be the first home on the Scottish mainland of St. Finan, a teacher of St. Columba. Acharacle, at the south of the Loch, is the site of the 1140 battle in which Somerled defeated the Norse to found the ruling dynasty of Lord of the Isles. During these times, the loch had strategic importance as a communications route through the mountains, as the short River Shiel was easily navigable in ancient times, however is no longer navigable as the depth drops to less than a foot. Alasdair mac Mhaighstir Alasdair, the poet and supporter of Bonnie Prince Charlie, was born and raised in the area. In 1745, after disembarking at Moidart, Bonnie Prince Charlie was rowed the length of the loch in order to raise his standard at Glenfinnan.
Loch Shiel is the location of the fictional Black Lake near Hogwarts in the film versions of the Harry Potter series. It is also the fictional birthplace of Connor and Duncan MacLeod from the Highlander franchise as well as the actual location of the boat scene with Ramirez in The Highlander (1986). The loch was also used in the filming of the movie The Master of Ballantrae starring Errol Flynn.