Inner Sea at a glance
- 38 maverage depth
- 33 mmedian depth
- 425 mmaximum depth
- 20,821 km²water area
Inner Sea is a sea. Inside its outline the GEBCO grid has about 20,821 km² of water, with an average depth of about 38 m (the middle value is 33 m) and a maximum of 425 m, found at 33.34° N, 131.97° E.
Open the map at the deepest cell and tap to read the depth.
How deep is each part of the Inner Sea?
The bar splits the Inner Sea's water by depth. Each colour is a depth band, and the shares add up to 100%.
- 0 to 200 m: 99.8%
- 200 to 1,000 m: 0.2%
- 1,000 to 4,000 m: 0%
- 4,000 to 6,000 m: 0%
- below 6,000 m: 0%
Named features near the deepest point: Tsushima Basin (361 km), Jeffrey Deep (526 km), Ōmurodashi (702 km), Yamato Ridge (719 km).
The Inner Sea if sea level dropped
The slider on the map lowers the sea in steps. This table shows how much of the Inner Sea's water would be land at each step.
| Sea level lowered by | Becomes land | Share of its water |
|---|---|---|
| 10 m | 2,099 km² | 10.1% |
| 20 m | 5,831 km² | 28% |
| 50 m | 15,003 km² | 72.1% |
| 80 m | 19,358 km² | 93% |
| 120 m | 20,640 km² | 99.1% |
| 200 m | 20,781 km² | 99.8% |
| 500 m | 20,821 km² | 100% |
| 1,000 m | 20,821 km² | 100% |
| 2,000 m | 20,821 km² | 100% |
| 3,000 m | 20,821 km² | 100% |
| 4,000 m | 20,821 km² | 100% |
| 6,000 m | 20,821 km² | 100% |
A simple bathtub model: it lowers the sea everywhere by the same amount and does not simulate how water would really drain.
Nearby seas
- Yellow Sea average depth about 46 m
- East China Sea average depth about 403 m
- Sea of Japan average depth about 1,725 m
- Bo Hai average depth about 18 m
- Philippine Sea average depth about 4,472 m
- Sea of Okhotsk average depth about 881 m
Nearest by the centre of each outline. All oceans and seas
Frequently asked questions
How deep is the Inner Sea?
On average about 38 m in the GEBCO grid (the middle value is 33 m). The deepest cell inside its outline is 425 m, at 33.34° N, 131.97° E.
How big is the Inner Sea?
About 20,821 km² of water inside its Natural Earth outline, counted from the grid cells that are below sea level.
How much of the Inner Sea would be land if sea level dropped?
With the sea 10 m lower, about 2,099 km² (10.1%) of its water would be land. At 6,000 m lower, 100% would be. This is a simple bathtub model that lowers the sea evenly everywhere.
Data: depths from the GEBCO_2026 grid, statistics worked out inside the Natural Earth outline of the sea. See data sources and licences. The GEBCO Grid should NOT be used for navigation or for any other purpose involving safety at sea.