Are the Bottoms of Earth's Bodies of Water Fully Mapped?

When it comes to mapping the ocean floor, the answer is not a straightforward 'yes' or 'no'. In certain areas, the seafloor has been mapped accurately, but there remains a significant amount of uncertainty in many regions. This dichotomy is largely due to the methods available for mapping and the vast size of the ocean itself.

Global Map of Seafloor

On one hand, mapping the ocean floor has made considerable progress. Most notably, the far parts of the seafloor were mapped using a combination of gravity changes and satellite radar technology. Satellites, such as those utilizing radar, have provided a rough but detailed map of the ocean surface. These variations in the ocean surface are directly related to the undulations of the seafloor beneath it.

Radar signal bounces off the ocean surface, and the differences in this signal reflect subtle changes in gravity. These changes can cause the ocean surface to vary from a simple ellipsoid by several meters, with horizontal resolution of a few kilometers. A notable example is the island of Hawaii, where the large gravity caused by the underwater volcano results in the ocean surface rising 24 feet around the island. Conversely, areas with significant depressions, such as the Mariana Trench, see the ocean surface drop by 36 feet.

Underwater Exploration and Challenges

Despite these advances, much of the seafloor still lacks detailed mapping. Traditional methods, such as echo sounding from ships, have not been able to provide the level of detail required in many areas. This challenge is particularly pronounced in smaller, subtle underwater features that might not be observable through satellite data alone. Submarine expeditions, while providing valuable data, still face the risk of running into uncharted areas—a recent incident involving a US submarine provides a cautionary tale.

Progress in Mapping Technology

There is noticeable progress being made, however. The proportion of the global ocean floor that has been thorough mapped is on the rise, now reaching just under a quarter of the total surface area. This progress, while significant, still leaves a large portion of the seafloor uncharted.

Modern multibeam sonar systems have begun to map about five percent of the global ocean floor with the necessary detail. These systems provide high-resolution information that unveils volcanic craters, shipwrecks, and other topographical features not visible through satellite or radar alone. While these advancements are improving our understanding of the seafloor, there is still a vast ocean yet to be explored.

Conclusion

In summary, while the ocean floor has seen significant mapping in key areas, much is yet to be explored. The vastness and complexity of the ocean present ongoing challenges for mapping technologies. Despite these challenges, the progress made through satellite radar and emerging sonar technologies offers a promising outlook for further exploration and understanding of the unseen depths of our planet's bodies of water.