GEBCO, the General Bathymetric Chart of the Oceans, is the international project that produces the main free global map of the ocean floor. This map uses its GEBCO_2026 grid.
Key takeaways
- GEBCO is the project behind the depth data on this map, and its grid is free to download under its terms of use.
- This map uses the GEBCO_2026 release, which has one value every 15 arc-seconds.
- GEBCO gives land elevations as well as ocean depths in one grid, so the coast is seamless.
- GEBCO says its grid should not be used for navigation or for safety at sea.
How GEBCO works
GEBCO stands for the General Bathymetric Chart of the Oceans. It produces a range of free ocean-mapping products, including a global bathymetric grid, a gazetteer of undersea feature names, a web map service and printable maps [1]. Its gridded datasets are global terrain models for ocean and land [1].
The grid is not a single survey. It is a compilation. The GEBCO_2026 Grid uses a base dataset from latitudes mostly between 50 degrees south and 60 degrees north that fuses land topography with measured and estimated seafloor depths, the estimates being predictions from satellite-derived gravity data [2]. On top of that base go gridded datasets from four regional centres of the Seabed 2030 Project, largely based on multibeam sonar data [2]. The result is blended so that the join between old and new data is smooth [2].
That is why the quality of the map varies from place to place. A cell built from a ship survey can show a narrow canyon. A cell built from satellite estimates cannot.
GEBCO also gives land. The same grid has elevation data in metres for the ocean and the land, on a 15 arc-second interval, in 43,200 rows and 86,400 columns [2]. So you can move across a coast without a gap, which is what lets this map put the deepest trench and the highest ground on one scale. See digital elevation model and arc-second for what that means.
The grid is published in releases. The one used here is GEBCO_2026, published in April 2026 [2].
An example from our data
Every depth you see when you tap this map comes from GEBCO. Challenger Deep, the deepest point in the grid, reads 10,927 m below sea level, and the highest ground reads 8,627 m above it. Set that highest ground on the bottom of the Mariana Trench and its top would still sit about 2,300 m under water.
GEBCO is also the source of the names. Our map labels 950 named undersea features, of which 300 have their own pages, such as the Mid-Atlantic Ridge. The homepage section on how the seabed is mapped puts the grid in context, and the data sources page has the full credit line and licence.
The thing people get wrong
Some people treat the GEBCO grid as an official chart for ships. It is not, and GEBCO says plainly that the grid should not be used for navigation or for any purpose involving safety at sea. Official nautical charts, made from dedicated surveys, are the tool for that.
A second misunderstanding is that every cell is a measurement. In the deep ocean far from ship tracks, the grid is partly an estimate. Treat it as a guide to the big picture, not as a survey.
GEBCO vs Seabed 2030
| GEBCO | Seabed 2030 | |
|---|---|---|
| What it is | The international group that produces the global grid | A project of the Nippon Foundation and GEBCO |
| Aim | Free, open ocean-floor data | A complete map of the seabed by 2030 [1] |
| Role | Publishes the grid | Gathers data from regional centres to feed it |
Frequently asked questions
Is GEBCO data free?
Yes. The grid can be downloaded as a global file or for areas you choose, under GEBCO's terms of use, which ask for credit. Our data sources page gives the credit line.
Can I use GEBCO for navigation?
No. GEBCO says its grid should not be used for navigation or for any purpose involving safety at sea. Use official nautical charts.
What is the difference between GEBCO and Seabed 2030?
GEBCO is the long-running organisation that produces the grid. Seabed 2030 is the project, run by the Nippon Foundation and GEBCO, that gathers data to complete it.
Sources
- GEBCO, General Bathymetric Chart of the Oceans.
- GEBCO_2026 Grid, GEBCO.
- Every figure from our own map is worked out from the datasets on the data sources page (checked against GEBCO_2026 grid).