Sea level 20 m lower at a glance
- 4.7 million km²seabed becomes land
- 3.2%of today's land area
- 98.7%of today's sea remains (357 million km²)
- 0of 10 land bridges open
With the sea 20 m lower than today, about 4.7 million km² of seabed becomes land, 3.2% of today's land area. 98.7% of today's sea, about 357 million km² of the 361.8 million km² connected to the open ocean, is still under water.
The exposed area counts only seabed connected to the open ocean. Lakes stay water, and basins below sea level on land, such as Death Valley, stay land. It is a simple bathtub model, not a forecast.
Land bridges at this sea level
None of the land bridges in our list is open at this step. The first, Doggerland (North Sea), opens when the sea is 50 m lower.
The list holds 10 places that we checked against the grid. It is not every land bridge there has been.
Seas that shrink most at 20 m lower
| Sea, gulf or bay | Becomes land | Share of its water |
|---|---|---|
| Sea of Azov | 36,729 km² | 100% |
| Bo Hai | 43,815 km² | 57.3% |
| Kattegat | 10,475 km² | 45.6% |
| East Siberian Sea | 221,916 km² | 36.8% |
| Persian Gulf | 84,598 km² | 35.6% |
| White Sea | 27,945 km² | 31.9% |
| Visayan Sea | 4,965 km² | 28.7% |
| Inner Sea | 5,831 km² | 28% |
The Caspian Sea is left out because it is a lake and stays water in this model.
Other sea levels
Frequently asked questions
How much land appears if sea level drops 20 m?
About 4.7 million km² of seabed becomes land, which is 3.2% of today's land area (147,036,202 km², lakes excluded). 98.7% of today's sea remains.
Which land bridges open at 20 m?
None of the land bridges in our list is open yet at this step.
Is this a forecast of sea level change?
No. It is a simple bathtub model that lowers the sea everywhere by the same amount, from today's coast, using the GEBCO_2026 grid. It does not simulate how the water would drain, how the land would adjust, or any past or future climate.
Data: land and depths from the GEBCO_2026 grid, lakes from Natural Earth. See data sources and licences. The GEBCO Grid should NOT be used for navigation or for any other purpose involving safety at sea.