Loch Shiel is a freshwater loch forming part of the border between Argyllshire and Inverness-shire located 12½ miles west of Fort William in the latter county. It extends for some 17½ miles in a generally north-east to south-west direction and is no more than a mile broad at its widest point. It is 393 feet deep at its deepest.
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 River Shiel drains to the sea in Loch Moidart near Castle Tioram. Loch Shiel should not be confused with Glen Shiel, 25 miles further north, 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 3,000ft 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, 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 were higher.
A ruined chapel can be found on the largest island said to be the first home on the 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. Alexander MacDonald, the famous poet and supporter of Bonnie Prince Charlie, was born and raised in the neighbourhood. In 1745, after disembarking at Moidart, he was rowed the length of the loch in order to raise his standard at Glenfinnan.