LakeMap – Swiss Lake Charts

LakeMap is the offline chart plotter for Swiss lakes: 22 surveyed lakes with bathymetry from the swisstopo swissBATHY3D dataset ship inside the app — depth contours, depth shading, seamarks and marinas all work with no connection at all.

DISCLAIMER
LakeMap is an independent app and is not affiliated with, endorsed by, or operated on behalf of any government authority (swisstopo, FOEN, MeteoSwiss or any other agency). It is not an official navigational aid: official charts and the shore storm-warning lights remain authoritative.

THE DIFFERENCE: DEPTHS FROM THE LIVE LAKE LEVEL
Ordinary charts show depths against a fixed datum. LakeMap computes with the current water level, using public hydrological gauge data from the Federal Office for the Environment FOEN (https://www.hydrodaten.admin.ch): the depth you see is today's depth — at low autumn levels just as after snowmelt.

PREDICTIVE SHALLOW-WATER ALERTS
The app projects your course 60 seconds ahead and warns in four tiers before the bottom comes up, with distinct alert tones. Unsurveyed water is treated as a hazard: zones without depth data render violet and raise their own alert tier instead of falsely looking safe.

CHART & NAVIGATION
• Depth contours and bands from swisstopo swissBATHY3D (https://www.swisstopo.admin.ch/en/height-model-swissbathy3d)
• Seamarks and buoys, harbours and marinas (OpenStreetMap, https://www.openstreetmap.org)
• Own position with smoothed course and speed (COG/SOG)
• Depth readout under your boat
• Automatic lake detection

WEATHER & WIND CUES
Hourly wind and gust forecast per lake, based on MeteoSwiss ICON model data provided via Open-Meteo (https://open-meteo.com), cached offline with visible age. In-app cues follow the wind thresholds of the Swiss storm-warning scheme — strong wind from 25 kn, storm from 33 kn — as published by MeteoSwiss (https://www.meteoswiss.admin.ch), and the app shows publicly available severe-weather alerts (https://meteoalarm.org). These in-app cues are informational and are not the official storm warning: the shore warning lights and official channels remain authoritative.

THE LAKES
Lake Zurich, Lake Constance, Lake Lucerne, Lake Thun, Lake Brienz, Lake Biel, Lake Neuchâtel, Lake Murten, Lake Geneva, Walensee, Lake Zug, Lago Maggiore, Hallwilersee, Ägerisee, Baldeggersee, Sempachersee, Sarnersee, Lac de Joux, Silsersee, Silvaplanersee, Lungernsee, Rotsee.

DATA SOURCES
• Bathymetry: © swisstopo — https://www.swisstopo.admin.ch/en/height-model-swissbathy3d
• Water levels: © FOEN — https://www.hydrodaten.admin.ch
• Weather: MeteoSwiss ICON via Open-Meteo — https://www.meteoswiss.admin.ch / https://open-meteo.com
• Weather alerts: MeteoAlarm — https://meteoalarm.org
• Seamarks & marinas: © OpenStreetMap contributors — https://www.openstreetmap.org