The average depth of the ocean globally is 3,700 meters. So, what lies beneath the deep sea? What kind of mysterious world is it?
According to modern scientists, human understanding of the deep sea in the last century was even less than our knowledge of the Solar System! However, with the advent of manned submersibles and unmanned underwater vehicles, humans have been able to explore part of the deep seabed.
Currently, only a few countries in the world can independently develop manned submersibles capable of reaching depths of 10,000 meters, such as China and the United States.
The pressure at the ocean depths is hundreds of times greater than atmospheric pressure at the surface. To withstand such high pressures, submersibles must be extremely pressure-resistant, and if they are manned, they also need to ensure the safety and comfort of those inside.
China’s deep-sea exploration vessel.
The area of the deep sea explored by humans currently occupies only a very small fraction of the total ocean area. The average depth of the global ocean is about 3,700 meters, while the ocean covers 70% of the Earth’s surface. Therefore, there are still many secrets hidden in the depths of the ocean that we may take a long time to uncover.
The deep sea refers to the deepest areas of the ocean, typically where the seabed is deeper than 200 meters. Due to the unique environment of the deep sea, factors such as light, pressure, temperature, and others are vastly different from those on land and in shallow waters, resulting in flora and fauna in the deep sea that are completely unlike what we commonly see.
The landscape of the deep sea is entirely different from what we usually see.
Here are the main environmental and ecological characteristics of the deep sea:
- Deep-sea environment: The temperature and pressure of its water are extremely high, reaching hundreds of atmospheres, with dim light and geological phenomena such as deep cold currents, underwater volcanoes, and hot springs.
- Deep-sea fish: Deep-sea fish are abundant and diverse, with many species appearing quite unusual. Besides having large mouths and diminished eyesight, they often emit light to attract prey or find mates. Compared to fish in shallow waters, deep-sea fish have less bone and muscle mass, and the cartilage content in their bones is much higher than that of shallow-water fish.
- Deep-sea benthic animals: Deep-sea benthic animals come in various forms, some looking quite beautiful while others appear very strange. These benthic creatures also play a crucial role in the deep-sea ecosystem.
- Deep-sea sediments: The organic matter in deep-sea sediments is unique because, under high pressure and low temperature, a significant amount of organic marine matter can gradually settle on the ocean floor.
- Hydrothermal organisms in the deep sea: Hydrothermal organisms refer to those living near hot springs in the deep sea. The temperature at the center of these hot springs can reach several hundred degrees Celsius. It is hard to imagine that a vast number of bacteria thrive in this harsh environment; some of these bacteria consume sulfides emitted from the hot springs and absorb energy from them.
- Deep-sea seabed topography: The topography of the deep seabed is often relatively complex and rugged, featuring many deep-sea faults, underwater cliffs, and trenches…
A lanternfish from the deep sea.
So why is the deep sea still a mystery to humanity?
Exploring the deep sea is not an easy task; it requires numerous skills, equipment, and expertise. There are many reasons that make it difficult for humans to access the mysteries of the deep sea, among which there are three main reasons:
First, the deep sea is an extremely harsh environment, with very low temperatures, very high pressures, and a lack of light. These factors make it difficult for humans to be safe here without the aid of protective equipment and respiratory support. Additionally, there are many toxic gases and radioactive substances in the deep sea that are hazardous to human health.
To explore the deep sea, scientists must use various techniques and technologies.
Second, the deep sea is a vast and complex environment, with varied terrains, geology, and diverse organisms. To explore the deep sea, scientists must employ various techniques and technologies, such as submarines, remote sensing devices, unmanned vehicles, or underwater robots. However, these tools still have limitations regarding mobility, signal transmission, and, in reality, they can only withstand pressure at certain depths.
Third, the deep sea is a relatively unexplored and poorly understood environment, filled with many mysteries and challenges. Estimates suggest that only about 5% of the ocean floor has been explored and mapped in detail. Nearly two-thirds of life on the ocean floor remains officially unidentified. Many natural phenomena and processes occurring in the deep sea are also not yet clearly explained.
Only about 5% of the ocean floor has been explored and mapped in detail.
These reasons explain why humans rarely explore the deep sea. However, this does not mean that humans are uninterested in the deep sea or overlook its values and potential. On the contrary, the deep sea is a valuable resource, a highlight for tourism and education, and a crucial factor in climate regulation and sustaining life on Earth. Therefore, exploring the deep sea is a necessary and meaningful mission for humanity in the future.
