Spilhaus Ocean Map Projection
The Spilhaus projection flips traditional cartographic priorities: instead of continuous landmasses, it preserves the integrity of the world ocean. It is an oblique map in a square where continents are torn apart to frame a single, connected body of water.
The world from the perspective of fish and ocean currents
Created in 1942 by the geophysicist and oceanographer Athelstan Spilhaus, this map represents a revolution in how we perceive the Earth. Traditional projections sever the oceans at the map borders (such as dividing the Pacific), complicating the study of ocean currents. Spilhaus shifted all cartographic cuts to landmasses, splitting America, Asia, and Africa, to show a globally connected water system centered on Antarctica.
Mathematically, it builds on an oblique aspect of the conformal Adams World in a Square II projection. As a conformal map, local shapes of islands and coastlines are accurately preserved. The side effect, however, is massive size distortion for landmasses located near the square's margins (like Asia or North America), which are stretched to colossal proportions.
Global Cartographic Grid
Distortion Properties
| Property | Characteristic |
|---|---|
| Area | ❌DistortedVarying (conformal projection, does not preserve area, enlarges regions near the edges) |
| Shape | ✅PreservedPreserved locally (conformal projection) |
| Distances | ✅PreservedDistorted globally, preserved only at specific scale-free points |
| Angles & Directions | ✅PreservedPreserved (conformal projection) |
| Continuity | ❌DistortedInterrupted on landmasses (Americas, Asia, and Africa are cut), preserves ocean continuity |
History & Origin
Designed in 1942 by the South African-American geophysicist and oceanographer Athelstan Spilhaus. Spilhaus aimed to create a map depicting the world ocean as a single, continuous body of water to better visualize marine currents and global water circulation. This projection is an oblique aspect of the Adams World in a Square II projection, rotated and centered on Antarctica.
Applications
Visualizing ocean currents, water temperature and salinity, the spread of marine pollution, and migration patterns of marine life. An invaluable tool in oceanography and aquatic ecosystem education.
How to read this map
Imagine viewing the Earth from the bottom (the South Pole) and pulling the continents apart like curtains toward the edges of a square screen, leaving the ocean intact in the middle.
- Locate Antarctica at the center of the map — it represents the heart of the world ocean.
- Trace a sea route from Africa to America; you will see it is completely uninterrupted.
- Find Northern Hemisphere countries (like Russia or Canada) — they are split and bloated in the corners.
- Use this map to analyze global ocean circulation, not to compare the sizes of nations.
What you gain and lose
Spilhaus sacrifices land continuity and area proportions to achieve absolute ocean continuity on a conformal square grid.
Oceanographic maps, illustrating climate change, ocean currents, marine migration, and lessons on geocurrent biases.
Political maps, land navigation, and teaching about continental areas.
✦ How do different countries look in this projection?
Analyze shape distortions of 5 countries in this cartographic projection and test them in the sandbox.
Poland is split and distorted near the corners of the square, illustrating how the projection treats Europe.
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The United States lies on the periphery, with its Pacific and Atlantic coasts positioned extremely far apart.
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Australia sits close to the oceanic center, maintaining a relatively faithful shape in the conformal grid.
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Brazil is cut and pulled toward the edges, forming part of the eastern boundary of the Atlantic.
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South Africa sits at a key junction connecting the Atlantic and Indian oceans without any interruption.
Test on map →Facts worth remembering
- Athelstan Spilhaus was a distinguished geophysicist and inventor, famous for the bathythermograph used to measure deep-sea temperatures.
- The projection was popularized again in 2018 by developers and cartographers working with modern GIS tools.
- The North Pole is not a single point but is instead projected along the edges and corners of the square.
Keep reading about maps that reshape intuition
Frequently Asked Questions
It is primarily used for oceanography and studying the seas. In this map, all of Earth's oceans form a single, continuous body of water, making it easier to analyze marine currents and global climate systems.
This is intentional. In order to keep the world ocean continuous on a flat sheet, Spilhaus shifted all cartographic cuts onto landmasses, splitting North America, South America, Asia, and Africa.
The center of the projection is focused on Antarctica and the Southern Ocean. The equator loops around the center, while the North Pole is split among the corners of the square.
No, it is a conformal (equal-angle) projection. It preserves local shapes and angles but heavily exaggerates the areas of landmasses positioned near the edges of the square.
Countries in the Northern Hemisphere far from the central oceans, such as Russia, Canada, and European nations. Many of them are split in half and pushed into the corners of the map.