Data sources & licences
Not for navigation. The GEBCO Grid should NOT be used for navigation or for any other purpose involving safety at sea.
Ocean Floor Map is an independent site. GEBCO, the IHO and the IOC do not endorse it or any application of the GEBCO Grid shown here.
The GEBCO_2026 Grid: how to cite it
Every depth and height on this site comes from the GEBCO_2026 Grid. The citation, as given in the readme that comes with the release:
GEBCO Bathymetric Compilation Group 2026 (2026). The GEBCO_2026 Grid - a continuous terrain model for oceans and land at 15 arc-second intervals. NERC EDS British Oceanographic Data Centre NOC. doi:10.5285/4f68d5c7-45eb-f999-e063-7086abc036fa
The short form used in the map corner is: GEBCO Compilation Group (2026) GEBCO 2026 Grid (doi: 10.5285/4f68d5c7-45eb-f999-e063-7086abc036fa). DOI: 10.5285/4f68d5c7-45eb-f999-e063-7086abc036fa. GEBCO grid page · GEBCO terms of use · British Oceanographic Data Centre record.
GEBCO terms of use
GEBCO's terms say, in its own words:
The GEBCO Grid is placed in the public domain and may be used free of charge.
The conditions, as GEBCO states them, are to:
- Acknowledge the source of The GEBCO Grid.
- Not use The GEBCO Grid in a way that suggests any official status or that GEBCO, or the IHO or IOC, endorses any particular application of The GEBCO Grid.
- Not mislead others or misrepresent The GEBCO Grid or its source.
And its safety warning:
The GEBCO Grid should NOT be used for navigation or for any other purpose involving safety at sea.
We follow all of these. The grid is credited on every page, in the map corner and in every image you download. Ocean Floor Map is independent: GEBCO, the International Hydrographic Organization (IHO) and the Intergovernmental Oceanographic Commission (IOC) have not endorsed it. GEBCO terms: public domain, free of charge, acknowledge the source. The CEDA archive record lists the Open Government Licence v3 and requires the catalogue citation.
What the grid is, and what it is not
We use the ice surface (standard grid, not sub-ice) version of the grid: 86,400 columns by 43,200 rows, one value every 15 arc-seconds (pixel-centre registration), in whole metres. That is about 460 m between values at the equator. Most of the deep ocean has not been surveyed by ship, and much of the grid there is predicted from satellite measurements of the sea surface, so the seabed looks smoother than it is. The deepest cell in the grid is 10,931 m below sea level and the highest is 8,627 m above it; the highest cell reads lower than the real summit of Everest because of the smoothing in the grid.
The map tiles are coarser than the grid. Each tile pixel at the highest zoom covers about 1.2 km at the equator, and the depth you read when you tap is taken from the pixel under your finger, so narrow trenches and sharp peaks read shallower or lower than in the full grid. Headline figures on the pages come from the full grid.
Data sources & licences
This site is built entirely on open data and open-source software. Thank you to everyone who collected, shared and maintains it. Here is exactly what we use and the licence each part comes with.
- Data version
- GEBCO_2026, ice-surface elevation, published 2026-04-22 (doi:10.5285/4f68d5c7-45eb-f999-e063-7086abc036fa); features, waters and levels generated 2026-10-13
- Last refreshed
- 2026-10-13
GEBCO_2026 Grid
Credit: GEBCO Bathymetric Compilation Group 2026 (2026). The GEBCO_2026 Grid - a continuous terrain model for oceans and land at 15 arc-second intervals. NERC EDS British Oceanographic Data Centre NOC. doi:10.5285/4f68d5c7-45eb-f999-e063-7086abc036fa
Used for: All depths and heights, the colour relief and shading, the "drain the oceans" land, the sea and ocean statistics, and the depth figure for every undersea feature. The ice-surface grid at 15 arc-second spacing is turned into map tiles, and we read the value back from the tile under a tap.
Licence: Public domain, with conditions of use
Source: https://www.gebco.net/data-products-gridded-bathymetry-data/gebco2026-grid
Version: GEBCO_2026 Grid, ice-surface elevation, published April 2026 (doi:10.5285/4f68d5c7-45eb-f999-e063-7086abc036fa)
Wikidata
Credit: Undersea feature names, positions and Wikipedia links from Wikidata (wikidata.org), CC0
Used for: The names, types and listed positions of trenches, ridges, seamounts, basins, canyons, fracture zones and plateaus, and Wikidata’s own depth figure where it gives one.
Licence: CC0 1.0
Source: https://www.wikidata.org/
Natural Earth
Credit: Ocean and sea outlines from Natural Earth (naturalearthdata.com), public domain
Used for: The outlines of the oceans, seas and gulfs (the depth statistics are worked out inside them) and the lakes cut out of the drained land.
Licence: Public domain
GeoNames
Credit: Town and city names and positions from GeoNames (geonames.org), CC BY 4.0
Used for: Town and city search (the cities15000 file).
Licence: CC BY 4.0
Source: https://www.geonames.org/
OpenStreetMap
Credit: © OpenStreetMap contributors, basemap by Protomaps, ODbL
Used for: Country borders and place names drawn over the relief.
Licence: ODbL
Source: https://protomaps.com/
Software
The map is drawn with MapLibre GL JS and PMTiles, and the site is built with Astro. These are open-source projects under their own licences.
Using our images and embeds
Images you download from the map and the embed code both carry the credits above. Please leave them in place.
Files we publish
The map is drawn from these files, which are made from the sources above by a script in our repository. They are served from our own data host.
| File | Size | What it holds |
|---|---|---|
| terrain.pmtiles | 691 MB | The grid as map tiles (Terrarium encoding, zoom 0 to 7): the colour relief, the shading and the depth read when you tap. |
| drain.pmtiles | 42 MB | The land at each of the 13 sea levels of the "drain the oceans" slider, as outlines. |
| features.pmtiles | 0.4 MB | The 950 named undersea features, as labelled points. |
| gazetteer.json | 1.8 MB | The names searched by the search box: towns and cities, undersea features, oceans and seas. |
Undersea feature names
The names, types and positions of undersea features come from Wikidata (CC0), not from the IHO-IOC GEBCO Gazetteer of Undersea Feature Names, whose terms of reuse are not stated. Wikidata gives one point for each feature, even for a very long trench, so we measure depth near that point as each page explains. Where Wikidata also records a depth we show it beside ours, without using it in our headline figures. 58 Wikidata items whose listed point is on land were left out.
How the numbers are worked out
Ocean and sea depth statistics are computed over the grid cells below sea level inside each Natural Earth outline, with each cell weighted by its true area. The land shown by the "drain the oceans" slider is the land at each sea level, worked out from a 1 arc-minute (about 1.85 km) average of the grid, simplified, with small islands and holes removed and Natural Earth lakes kept as water. Inland basins below sea level stay land. Exposed areas count only seabed connected to the open ocean. It is a bathtub model, not a forecast.