Loch Shiel and Glenfinnan monument
|Location||Lochaber, Highland, Scotland|
|Primary inflows||River Finnan, Callop River, River Polloch|
|Primary outflows||River Shiel|
|Basin countries||United Kingdom|
|Max. length||17 1⁄2 mi (28 km)|
|Surface area||19.6 km2 (7.6 sq mi)|
|Average depth||133 ft (41 m)|
|Max. depth||393 ft (120 m)|
|Water volume||0.8 km3 (0.19 cu mi)|
|Residence time||1.37 year|
|Surface elevation||15 ft (4.6 m)|
|Settlements||Glenfinnan, Ardshealach, Acharacle|
Loch Shiel (Scottish Gaelic: Loch Seile) is a 17 1⁄2-mile-long (28 km)  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.
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, 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.