Gulf of Tonkin at a glance
- 36 maverage depth
- 33 mmedian depth
- 86 mmaximum depth
- 111,363 km²water area
Gulf of Tonkin is a gulf. Inside its outline the GEBCO grid has about 111,363 km² of water, with an average depth of about 36 m (the middle value is 33 m) and a maximum of 86 m, found at 18.32° N, 107.94° E.
Open the map at the deepest cell and tap to read the depth.
How deep is each part of the Gulf of Tonkin?
The bar splits the Gulf of Tonkin's water by depth. Each colour is a depth band, and the shares add up to 100%.
- 0 to 200 m: 100%
- 200 to 1,000 m: 0%
- 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: Reed Tablemount (1,231 km), Manila Trench (1,246 km), Unnamed volcano (1,571 km), Iriomote Submarine Volcano (1,793 km).
The Gulf of Tonkin if sea level dropped
The slider on the map lowers the sea in steps. This table shows how much of the Gulf of Tonkin's water would be land at each step.
| Sea level lowered by | Becomes land | Share of its water |
|---|---|---|
| 10 m | 10,812 km² | 9.7% |
| 20 m | 28,005 km² | 25.1% |
| 50 m | 80,307 km² | 72.1% |
| 80 m | 111,320 km² | 100% |
| 120 m | 111,363 km² | 100% |
| 200 m | 111,363 km² | 100% |
| 500 m | 111,363 km² | 100% |
| 1,000 m | 111,363 km² | 100% |
| 2,000 m | 111,363 km² | 100% |
| 3,000 m | 111,363 km² | 100% |
| 4,000 m | 111,363 km² | 100% |
| 6,000 m | 111,363 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
- South China Sea average depth about 1,354 m
- Gulf of Thailand average depth about 42 m
- Andaman Sea average depth about 1,071 m
- Sibuyan Sea average depth about 608 m
- Sulu Sea average depth about 1,639 m
- Visayan Sea average depth about 118 m
Nearest by the centre of each outline. All oceans and seas
Frequently asked questions
How deep is the Gulf of Tonkin?
On average about 36 m in the GEBCO grid (the middle value is 33 m). The deepest cell inside its outline is 86 m, at 18.32° N, 107.94° E.
How big is the Gulf of Tonkin?
About 111,363 km² of water inside its Natural Earth outline, counted from the grid cells that are below sea level.
How much of the Gulf of Tonkin would be land if sea level dropped?
With the sea 10 m lower, about 10,812 km² (9.7%) 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 gulf. See data sources and licences. The GEBCO Grid should NOT be used for navigation or for any other purpose involving safety at sea.