Lochs

Loch is the Scottish Gaelic word for a lake or sea inlet. In Scotland the term is used for most large bodies of water, regardless of whether they are inland freshwater lakes or coastal inlets. Outside Scotland the word lake is more common, but many large Scottish bodies retain the name loch. Some lochs are freshwater; others are tidal or seawater inlets connected to the sea.

Most lochs were formed during the last glacial period by erosion of bedrock and subsequent infilling with meltwater. They are broadly categorized as freshwater lochs and sea lochs. Freshwater lochs collect rainwater and river inflows; sea lochs are connected to the sea and show tidal exchange, often with brackish water. Artificial lochs, created as reservoirs, serve water supply or hydroelectric generation.

Notable lochs include Loch Lomond, the largest freshwater loch by surface area in Great Britain; Loch Ness, famous for its depth and legend; Loch Morar, the deepest freshwater body in Scotland; and Loch Katrine, an important historical reservoir supplying Glasgow. The Scottish coast contains numerous sea lochs, such as Loch Fyne and Loch Etive, which are long, narrow sea inlets with marine influence.

Lochs are central to Scotland's ecology and economy. They support diverse aquatic life and bird habitats, provide drinking water and hydroelectric power, and sustain fishing and tourism. Recreational activities such as boating, fishing, and hiking around their shores are common. Conservation and water-quality monitoring are managed by national and local authorities to protect these landscapes and their communities.