Ocean Floor Map

Supply Reef: depth and map

Seamount or guyot: 102 m to the summit (GEBCO_2026 grid).

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Sea level in metres below today’s. A simple bathtub model: it lowers the sea everywhere by the same amount and does not simulate how the water would really drain.

Key

Sea depth

  • Deeper than 6,000 m
  • 4,000 to 6,000 m
  • 2,000 to 4,000 m
  • 1,000 to 2,000 m
  • 200 to 1,000 m
  • Shallower than 200 m (the continental shelf)

Land height

  • Land up to 500 m
  • 500 to 2,000 m
  • Above 2,000 m

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How to read the map. Darker blue is deeper water. Tap anywhere to see how deep the sea is there, or how high the land is, and the nearest named undersea feature. Depths come from the GEBCO_2026 grid, which in most of the deep ocean is predicted from satellite measurements of the sea surface rather than surveyed by ship, and the map’s tiles are coarser than the grid, so narrow trenches read shallower on the map than their true depth. Not for navigation.

Supply Reef at a glance

  • 102 mto the summit, in the grid
  • Seamount or guyottype of feature
  • 20.14° N, 145.10° Elisted point
  • Northern Mariana Islandsnearest country, about 18 km

Supply Reef is a seamount or guyot. Its summit is about 102 m below the surface in the GEBCO grid. That figure is the depth of the shallowest cell within 10 km of its listed point, which is its summit. The nearest country in our list is Northern Mariana Islands, about 18 km from its listed point.

Open the main map at its summit and tap anywhere to read the depth.

How deep is the Supply Reef?

The grid figure is 102 m. We measured it as the depth of the shallowest cell within 10 km of its listed point, which is its summit. The cell is at 20.14° N, 145.10° E. The GEBCO_2026 grid has a value every 15 arc-seconds, about 460 m at the equator, so a very narrow feature can be a little deeper or shallower in reality than any grid cell shows.

Wikidata has no depth figure for this feature, so the grid is our only source for it.

About seamounts and guyots

A seamount is an underwater mountain, usually an extinct volcano. A guyot is a seamount with a flat top, worn flat by waves when it once stood at the surface.

This site lists 420 seamounts and guyots, 115 of them with their own indexed page. See all undersea features.

Nearby undersea features

Distances are between listed points. A long feature such as a trench or ridge has a single listed point on Wikidata.

The highest seamount summits in our list

Frequently asked questions

How deep is the top of Supply Reef?

In the GEBCO grid the figure is 102 m. That is the depth of the shallowest cell within 10 km of its listed point, which is its summit.

Where is the Supply Reef?

Its listed point is 20.14° N, 145.10° E, about 18 km from Northern Mariana Islands. The grid's shallowest cell for it is at 20.14° N, 145.10° E.

Data: depth from the GEBCO_2026 grid. Name and position from Wikidata Q4178062 (CC0); Wikipedia article. See data sources and licences. The GEBCO Grid should NOT be used for navigation or for any other purpose involving safety at sea.

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