Raise the water from 0 to 1 metre, then 2 metres, and watch low ground spread inland around Florida, Hawaii, the Netherlands, or any coast you choose. The map marks elevation, not a forecast year.
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Coast-by-coast elevation guide
A global average hides the shape of each coast. Here you can set a water height in whole metres, zoom to one place, and compare the same shoreline at several levels. Blue means the terrain cell is lower than your selected number. It does not mean that water can necessarily reach that cell.
For every terrain pixel, the map asks one question: is its elevation below the selected height? If yes, it turns blue. That rule makes broad elevation patterns easy to compare, but it does not route water from the sea or stop it at a levee.
A coast floods through connected paths. Water moves through inlets, rivers, canals, drains, and gaps in protection. A height-only map does not solve that network. It colors an inland basin even when higher ground separates it from the ocean, and it may miss the effect of a narrow channel that is smaller than a terrain pixel. Small defenses may not appear. Storm surge can exceed the selected height, while sinking land changes local relative sea level.
NOAA's coastal viewer handles connectivity and local tidal datums for the United States, yet NOAA still describes its own product as a screening tool rather than a site forecast. Its guidance says to examine broad exposure, not the exact edge of a colored polygon. Use a local model for property or engineering decisions.
One metre equals 3.28 feet and two metres equals 6.56 feet. NOAA publishes Florida inundation layers in one-foot steps from 0 to 10 feet, so its 3-foot and 7-foot layers are the closest whole-foot checks for these two views. Look at Miami-Dade, the Keys, and the southwest coast, but compare patterns rather than individual streets.
Hawaii's state exposure data includes a 3.2-foot scenario, only 2 centimetres short of one metre. That model combines passive flooding, annual high-wave flooding, and erosion. This page shows elevation alone, so the official layer will not match its blue band.
The Netherlands is a different test. The Dutch government reports that 25 percent of the country is already below sea level. If those areas turn blue at 0 m, the map is identifying low terrain, not claiming that the sea currently covers it. Dikes, dunes, pumps, and managed waterways are the missing part of that picture.
The elevation layer is the public Mapzen Terrain Tiles collection in the AWS Open Data Registry. MapLibre decodes 256-pixel Terrarium PNG tiles through zoom 15 and applies the selected threshold. Esri World Imagery supplies the basemap. The calculation does not include tides, hydrological connectivity, waves, erosion, subsidence, future construction, or a date scenario. For U.S. planning work, compare the result with the official NOAA Sea Level Rise Viewer and its mapping-confidence layer.
Sources: AWS Terrain Tiles, NOAA Sea Level Rise Viewer, Hawaii 3.2-foot exposure layer, and Government of the Netherlands.
One metre is 3.28 feet. A height-threshold map marks terrain below that level, which reveals broad low-lying zones but cannot predict the exact waterline because local tides, drainage, defenses, and land motion also matter.
The threshold doubles from 3.28 to 6.56 feet, so every terrain cell between those elevations joins the blue area. On a flat delta or barrier-island coast, that extra vertical metre can produce a much wider horizontal change than it does beside cliffs.
No. Blue means the terrain value is below the chosen height. The calculation does not test whether that spot connects to the ocean, whether a barrier blocks water, or whether pumps and drainage change the outcome.
Some inland terrain sits below the selected elevation but has no open path to the sea. Because this is a height test rather than a hydrological model, those closed depressions are colored along with connected coastal land.
No. A selected height is not a date. The timing at one coast depends on future emissions, ice-sheet response, ocean circulation, gravity, and local vertical land motion, none of which this terrain comparison calculates.
This map compares terrain with a chosen water height. It does not predict flood timing or replace a local hazard study.
