Only 23 percent of the ocean floor has been discovered
It specifically refers to the meager amount of data available about the ocean floor and predates the deepest part of the ocean, the Mariana Trench (1960), and the first Moon landing (1969). This citation also predates the practice of using ship-mounted echo-sounders to map the sea floor from acoustic data, known as swath bathymetry. Nearly a quarter of the world’s ocean floor (23.4 percent, to be exact) has been mapped at a high resolution. This is about 120 million square kilometers, or about three times the total surface area of the Moon. This may be the reason why the comparison has shifted towards Mars, which has a surface area of 145 million square kilometres.
Furthermore, high-resolution maps do not represent complete information. The deep ocean must be considered in three dimensions – and, unlike the Moon, it is a diverse and dynamic ecosystem.
a surprising number of visitors
Another related and inaccurate comparison is that more people have set foot on the Moon than have visited the deepest point on Earth. It is difficult to confirm this statement. “The deepest place on Earth” may refer to the Mariana Trench, or its deepest part (Challenger Deep, named after the British survey ship HMS Challenger). Nevertheless, at least 27 and 40 or more people have visited Challenger Deep by the beginning of 2023. On the other hand, only 12 people have “set foot” on the Moon and 24 have visited it.
Out of sight, out of mind
So why do people keep saying that we know more about the Moon or Mars than about the deep ocean? It seems natural to compare the deep sea with space. Both are dark, scary and distant. But we can easily see the moon just by looking upwards. Being able to see it, we take it for granted more easily than the very deep parts of the ocean. We can see the moon waxing and waning and we can feel the push and pull of the tides.
It seems that we know more about the Moon than about the deep sea, because we are forced to accept its presence. It holds a place in our lives which cannot be said of the deep sea. We don’t think much about the deep sea unless we’re watching a documentary or horror movie, or perhaps reading about some “terrible extraterrestrial monster” that has emerged from the deep sea.
a useful analogy
While the deep ocean is physically inaccessible, comparing it to space may provide a useful analogy for ecosystems. But some deep-sea scientists argue that the continued isolation of the deep ocean underlies the vast amount of research that has come out about it in recent decades. Deep-sea biology is consistently referred to as a system that itself knows little about its field of study, when compared to a relatively small, barren reef devoid of atmosphere, water, and life. Yet this self-deprecating line is repeated by scientists themselves, who know that highlighting the lack of knowledge about the deep sea helps fuel the need for ocean research. Ultimately, we know more about the Moon than about the deep ocean, an idea that is itself about 70 years old. We know a lot more about the deep sea—but there’s still a lot more to learn.
(Prema Arasu, The University of Western Australia, Alan Jamieson and Thomas Linley, Newcastle University)
