Lakes of Switzerland: Interactive Map
Lakes of Switzerland has grown from a collection of GeoJSON files into a reproducible geodata project with its own interactive map. The current dataset contains 18,004 valid standing-water geometries from the 2026 release of swissTLM3D.
The viewer makes that detail approachable: search for a lake, inspect its complete shoreline geometry and place it in context with terrain, rivers and the exact Swiss boundary. The dataset and the full build pipeline remain openly available on GitHub.
A Dataset You Can Explore
The interactive Lakes of Switzerland map opens with the entire country in view. Its search accepts lake names and identifiers, and selecting a polygon reveals the lake ID, countries, geometry type, number of vertices and interior rings. Named lakes also receive map tooltips, while unnamed water features remain part of the complete dataset.
The selected shoreline is drawn from the full source coordinates without client-side geometry simplification. This is particularly useful when checking detailed shorelines, islands or multipart geometries instead of looking only at a generalized overview.
Terrain and Rivers as Context
Two optional layers help explain why water is where it is. A multidirectional swissALTI3D hillshade shows the terrain and relative elevation, while the BAFU river layer visualizes waterways with widths based on their Strahler network order. Both layers can be toggled independently and remain separate from the downloadable lake data.
An unsimplified swissBOUNDARIES3D polygon defines the national outline. The map clips its contextual layers to that boundary and displays Swiss lakes together with the complete geometries of the important cross-border lakes.
Complete Cross-Border Lakes
National datasets often stop at the border, which can leave a lake visibly cut in two. The current swissTLM3D source already contains the complete water surfaces for four major cross-border lakes, so the build retains them without substituting coarser third-party geometry:
- Lake Constance across Switzerland, Germany and Austria
- Lake Geneva across Switzerland and France
- Lake Maggiore across Switzerland and Italy
- Lake Lugano across Switzerland and Italy
Lake Constance is represented as a valid multipart geometry. Its Upper Lake and Lower Lake components remain topologically separate rather than being joined by an invented polygon through the Seerhein.
Built Reproducibly from Official Geodata
The master dataset is generated from the Federal Office of Topography's swissTLM3D 2.4, release 2026-02. Water polygons come from TLM_BODENBEDECKUNG; official names and stable water identifiers are matched from TLM_STEHENDES_GEWAESSER through their shared shoreline geometry.
The build keeps every standing-water polygon without a minimum-area filter. It validates all 18,004 geometries, checks that no features overlap and records the result in a machine-readable build manifest. Coordinates are exported in WGS84 longitude-latitude order as RFC 7946 GeoJSON, with no geometric simplification.
Anyone can rebuild and test the result with the documented Python workflow. The source release, coordinate reference systems, checksums, licences and treatment of border lakes are recorded alongside the code, making the output traceable rather than a one-off map export.
Open Map, Open Download
The viewer is deployed as a static GitHub Pages site and loads the same versioned GeoJSON that is available for download. This keeps the project useful in two ways: the map offers a quick visual way to discover and inspect lakes, while the repository provides the data and tooling for web maps, dashboards, analysis or new geospatial applications.
Explore the interactive map or view the source and dataset on GitHub.
Technologies
- GeoJSON
- Python
- GeoPandas
- Leaflet
- GitHub Pages
Tags
- Lakes
- Maps
- Open Data