Loch Lomond is a large freshwater loch in Scotland whose body of water is defined by its physical extent, depth, and catchment characteristics. This article explains the key measurable attributes of the loch, including its surface area, maximum and average depth, water volume, and shoreline length, alongside the origin of its outflow and the main islands within its basin. The aim is to provide clear, verifiable facts about the lake itself rather than myths or legends, drawing on authoritative geographic and hydrological sources.
Key measurable attributes of Loch Lomond
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Surface area | Approximately 71 km² (27.5 sq mi) | Survey/official data |
| Maximum depth | About 190 m (620 ft) | Bathymetric survey |
| Average depth | Approximately 37 m (121 ft) | Survey averages |
| Water volume | Roughly 2.6 km³ (0.62 cu mi) | Volume calculations |
| Shoreline length | Estimated 80 km (about 50 miles) | Coastline measurement |
| Primary outflow | River Leven toward Greenock and the Firth of Clyde | Hydrological records |
Geology and catchment context
Loch Lomond was shaped by glacial activity during the last ice age, which carved its deep basin into the Highland Boundary Fault zone. The loch lies partly within the Loch Lomond and The Trossachs National Park and drains a catchment area significantly larger than its surface water area. Its basin contains a mix of bedrock, sediments, and organic material, influencing water clarity and ecology. Understanding the broader geological context helps explain why the loch holds so much water and how its form has remained relatively stable over centuries.
Islands and shoreline features
Inward-facing shorelines and islands are among the most visible elements of Loch Lomond’s body of water. The loch contains around 30 named islands, with Inchmurrin, Creinch, Torrinch, and Inchconnachan among the largest. Many islands host small structures and histories tied to local use and conservation. The shoreline varies from steep, rocky sections to more gradual embayments, contributing to diverse habitats and local microclimates.
- Inchmurrin: the largest freshwater island in the British Isles
- Creinch and Torrinch: often grouped as the Northern Islands
- Inchconnachan: known for its small population and reserve status
Hydrology and outflow
The primary river flowing into Loch Lomond is not its main outlet; instead, the loch generally drains southeast via the River Leven, which meets the Firth of Clyde near Greenock. This outflow governs downstream water levels and connects the loch to broader marine systems. Flow rates vary with rainfall and season, but the Leven provides a consistent conveyance for excess water. Regulation and monitoring influence local ecology, navigation, and water management in both the loch and the lower river.
Data context and measurement notes
Because Loch Lomond is a natural lake with variable shorelines and changing water levels, exact figures can differ slightly between surveys. Shoreline length is sensitive to measurement scale, while depth readings vary by source and survey technique. Managed by entities such as NatureScot and supported by historical charting, the numbers cited here reflect the best available authoritative estimates. They are intended as stable reference points rather than transient statistics.
Taken together, the physical measures of Loch Lomond—its area, depth, volume, islands, and outflow—paint a clear picture of a major Highland loch with enduring geographic and ecological importance. For visitors, researchers, and local stakeholders, these factual baselines support informed discussion about land use, conservation, and water management around the body of water known as Loch Lomond.