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A thought experiment

Vienna by the sea

From which sea level would your address have a beach? The sea comes up the Danube, as in our video: scroll through the story or look at the map yourself.

172 m

The water reaches St. Stephen’s · 46 % of Vienna under water

  1. This is Vienna

    Vienna’s official lowest point lies in the Lobau, 151 m above the Adriatic. What if the sea came all the way here? Keep scrolling and it rises.

  2. 151 m: the sea stands before the Lobau

    It comes up the Danube bed from the east. In the terrain model, parts of the floodplain behind it lie even lower than 151 m, but the flood protection dam still keeps it out.

  3. 155 m: the dam overflows

    All at once the Lobau fills up: from 154 to 155 m, the share of Vienna under water jumps from 1.3 to 5.7 %. Being low is not enough, the water has to get there.

  4. 157 m: the sea is in the Danube Canal

    At the edge of the Inner City it fills the Danube Canal; St. Stephen’s is another 15 m up. Yet 11 % of Vienna is already under water, mostly along the Danube.

  5. 172 m: the water reaches St. Stephen’s

    Water on Stephansplatz. 46 % of Vienna is now under water.

  6. 183 m: half the city is gone

    10 of 23 districts are more than half under water. Hernals keeps half of itself dry the longest: until 300 m.

  7. 206 m: a beach 14 million years old

    In Nußdorf the waves reach surf boulders of a real sea. Back then the Vienna Basin was sea and the Vienna Woods were its coast.

  8. 250 m: the Vienna Woods are coast again

    78 % of Vienna is under water. What stays dry is mostly the Vienna Woods, at whose edge the coast already ran 14 million years ago.

  9. Honestly: a thought experiment

    Even if all the ice on Earth melted, the sea would rise by about 65 m, and Vienna stays dry. We are affected all the same: Austria is already about 3.1 °C warmer than before industrialisation, more than twice the global average.

  10. Your turn

    Search your address or drag the slider: from which sea level would you have a beach?

    Move and zoom the map with two fingers.

shallowdeepsurf

From how many metres does your district get a beach?

Beach from: the sea level at which the sea first reaches the district. Half: from here half of the district is under water, all: even its highest point. The higher a district climbs, the further apart the numbers lie. Tap a district.

150 m300 m

* Rounded to whole metres. In Donaustadt and Simmering the sea first reaches the Danube’s water surface, still below Vienna’s official lowest point; as in the video, that point, 151 m in the Lobau, applies as the lower limit.

Around 14 million years ago there really was sea here

The Vienna Basin was sea, the edge of the Vienna Woods its coast. In Nußdorf, surf boulders of this sea lie directly on the flysch; in Eichelhofstraße they have been a natural monument since 1955.

Teeth of the megalodon were found in Nußdorf and Kalksburg, skeletons of sea cows west of Dornbacher Straße in 1886. St. Stephen’s Cathedral is built almost entirely of Leitha limestone, which formed on the shores of the seas of that time.

That the old beach in Nußdorf lies at exactly 206 m today is a coincidence: the ground has warped since. Beach deposits of the same sea lie at 266 m in Kalksburg and at 285 m on Kahlenberger Straße.

How the map is computed
  • Terrain: DGM Austria, 10 m. In Vienna via the Terrain Tiles at zoom 14 (6.4 m per pixel), around it at zoom 12 (about 25 m); elevations in metres above the Adriatic.
  • Connected, not just low. A spot is under water when a path through terrain below the sea level connects it to the Danube downstream, in steps of 0.5 m. A hollow behind a ridge only floods when the sea reaches the ridge.
  • The same computation as the video. Inside Vienna, map and video use the same terrain and the same rule; the map was checked against the video’s data pixel by pixel; “beach from” and “half” match the video for every district.
What the map does not know
  • The water line is a contour in today’s terrain: no erosion, no landslides, no uplift of the crust.
  • Buildings and bridges are not in the terrain model; dams and embankments are, as terrain.
  • Elevations are accurate to about a metre in Vienna (terrain model 10 m), around it to a few metres.

Sources for the video “Vienna by the sea”

Watch the video:wohnwahn on TikTokwohnwahn on Instagramwohnwahn on YouTube

Data

For the film we cropped, converted and redrew the data.

Google 3D

Vienna today, the view from the Leopoldsberg: Google’s photorealistic 3D. In the film the credit stays in the picture for as long as Google’s image is visible: Google · Kartendaten: Landsat / Copernicus, Data SIO, NOAA, U.S. Navy, NGA, GEBCO, Airbus

Picture

  1. Thomas Dahlstrøm Nielsen, Südturm (Stephansdom) - 2026 (b), 2026. Wikimedia Commons. Licence: CC BY 4.0. Change: cropped, slow pan from the shaft to the spire.

AI, voice and music

The sea, the coast and the pictures of the ancient sea are painted and animated with AI, following our data. Voice, music and sound effects are AI-generated (ElevenLabs).