Why Is It so Hard to Map the Ocean Floor? | The Economist

The Economist
The EconomistApr 28, 2026

Why It Matters

A comprehensive seafloor map is essential for climate forecasting, resource discovery, and maritime security, yet geopolitical barriers and high costs threaten progress.

Key Takeaways

  • Only 27% of seafloor directly measured; 73% remains unknown.
  • Sound‑based echo‑sounding is the primary, slow method for mapping.
  • Multi‑beam sonar creates denser tracks; single‑beam leaves gaps.
  • Geopolitical and commercial secrecy delays release of existing data.
  • Seabed 2030 aims to map all oceans, costing up to $5 billion.

Summary

The Economist video examines why charting the ocean floor remains a monumental challenge and highlights the ambitious Seabed 2030 initiative aimed at completing a global map. While satellite radar can image land in days, water blocks radio waves, forcing researchers to rely on acoustic echo‑sounders mounted on ships.

Only about 27% of the seafloor has been directly surveyed; the remaining 73% is inferred from sparse data. Early single‑beam sonar left thin, crisscrossing tracks, whereas modern multi‑beam systems produce broader swaths, yet large swaths—especially in shallow, economically sensitive zones—remain unmapped. Geopolitical concerns, defense priorities, and commercial interests cause nations and corporations to withhold existing bathymetric data.

The video cites the Titanic disaster as the catalyst for sonar development and notes that trenches, critical for extreme geology and biology research, are among the best‑mapped regions. In contrast, shallow continental shelves within exclusive economic zones are the least surveyed, reflecting both technical and strategic barriers.

Mapping the full ocean floor could cost up to $5 billion and would take a single vessel two centuries, underscoring the need for coordinated international data sharing. Achieving a complete map would unlock new resources, improve climate models, and enhance maritime safety, making the effort a strategic priority for governments and industry alike.

Original Description

Humans know more about the surface of Mars than Earth’s ocean floor. Only 27% of the seabed has been mapped—the rest is still an estimate. Why is the ocean floor so hard to chart?
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