News archive
Earlier updates. The latest note stays on the News page.
August 2026 — LAT instead of Mean Sea Level
Mean Sea Level — MSL — will have to wait. Computing it needs larger datasets, meaning long time series. How MSL is determined is also not internationally uniform.
Using so-called LAT — Lowest Astronomical Tide — is a little simpler. That datum is published by the individual European countries.
July 2026 — Mean Sea Level, country by country
I’m rolling out Mean Sea Level (MSL) as the reference for the interactive sea-level map — not all at once, but peu à peu for every country already shown on the map: Germany, the Netherlands, Belgium, France, the United Kingdom, Denmark, and Norway.
Until now, many stations reported water levels against local gauge zero. That works fine for a single harbour, but comparing coasts across borders meant juggling different datums in your head. Referencing values to MSL makes heights comparable at a glance and should make the map more convenient for everyday checks — whether you’re reading one station or scanning a whole stretch of coast.
The switch happens gradually as each country’s offsets and station metadata are verified. If a region still looks “gauge-zero native,” it simply hasn’t been migrated yet — it will follow. Open the map to see the latest state as coverage expands.