People often use the dry seas and rotten rocks to describe a long time, and use the words "higher than the sky and deeper than the sea" to describe deep feelings. But how deep is the ocean? In the 19th century, people began to sail around the world to explore the deep sea. At that time, the research ships were actually warships, and the sailors were also naval soldiers. Their method of sounding the depth is very simple: take a shell, tie it to a cable, and throw it into the sea. After the shell touches the sea floor, pull the cable up and measure the length. The length of the cable in the water is considered as the depth of the sea. The accuracy of this "measurement" can be imagined, and the conclusion drawn is a bit outrageous today-the seabed is basically flat. The true scientific measurement of the depth of the ocean began in the 20th century. After the First World War, the Germans invented the technology of sound sounding: artificially made sound waves are shot from the ship to the seabed and reflected back. The water depth can be accurately measured based on the time it takes for the sound waves to go back and forth. This sonar sounding technology has been used to this day.
Now we know that the average water depth of the ocean is about 3680 meters, and the deep sea area with a water depth of more than 2000 meters is the absolute protagonist of the ocean, accounting for 84% of the ocean area. The shallow waters we know, such as coral reefs and algae forests, only account for a small part of the ocean area. Compared with the ocean, the average altitude of the earth's land is about 800 meters. Even the famous roof of the world-the Qinghai-Tibet Plateau, has an area of only 2.4 million square kilometers and an average altitude of only 4500 meters. In the ocean, the ocean basin with an average water depth of 5000 meters accounts for 40% of the earth's total area, exceeding 200 million square kilometers. If the Qinghai-Tibet Plateau is placed in the deep sea, most of it will be submerged in the vast ocean, and only scattered small islands will emerge from the water!
We often describe mountains as unattainable. In fact, the ocean is even more unfathomable: the deepest place on earth, the Mariana Trench, has a water depth of 11034 meters. If you put Mount Everest, the highest mountain in the world, into the Mariana Trench, the peak is more than 2000 meters away from the water! Whether the mountains are high or the seas are deep on the earth, you must know the answer!