More than 70 percent of the Earth’s surface is covered by water and it is sometimes referred to as “the blue planet.” Most original life forms evolved in the ocean, and to this day, the marine environment maintains a biodiversity not found in any other ecosystem. Humans are highly dependent on the ocean.
The expression “the seven seas” was used in the past by sailors who sailed across all the world’s oceans. These include the North Pacific Ocean, South Pacific Ocean, North Atlantic Ocean, South Atlantic Ocean, Arctic Ocean (Northern Ocean), Southern Ocean (Antarctic Ocean), and the Indian Ocean. The world ocean, also known as the oceans, is defined as the interconnected water area surrounding the Earth’s continents. The world ocean is divided into three oceans: the Pacific Ocean, the Atlantic Ocean, and the Indian Ocean, with the Pacific Ocean being the largest, covering over 30 percent of the Earth’s surface. Sometimes, the Antarctic Ocean is also considered a separate ocean. The three oceans include delimited seas or sub-seas. A sub-sea or semi-enclosed sea is a delimited part of an ocean. For example, the North Sea, the Arctic Ocean, and the Mediterranean Sea are sub-seas of the Atlantic Ocean.
Several of the world’s seas are relatively warm, but the average temperature of the world’s oceans is only around 3.5 degrees Celsius. This is because the large deep-water basins consist of cold polar water.
A large portion of the open sea areas does not belong to any individual country and is often referred to as the “high seas” or deep sea. These areas constitute almost half of the Earth’s surface, two-thirds of the world’s ocean area, and 95 percent of the world’s ocean volume. The deep sea is not subject to national laws and, in practice, belongs to everyone. The United Nations has long negotiated how these areas should be managed. After more than ten years of intense negotiations, the UN adopted a new binding treaty for the sustainable use of biodiversity in areas beyond national jurisdiction in 2023. This is a step towards fulfilling the global commitments of the international biodiversity agreement from 2022, where the goal is to protect at least 30 percent of the ocean by 2030.
Despite the ocean being a place where various organisms thrive, there are many extreme environments in the sea. From temperatures below freezing to near boiling points in hot underwater springs. Where the sea meets the land, the waves are powerful, UV radiation is high, and it is home to a large biodiversity. Some organisms utilize a wide range of habitats, while others specialize in a single type of environment.
The deep sea is a hostile environment for us humans. At a depth of 30 meters, most light is gone, at 70 to 80 meters, most of the oxygen disappears, and the pressure at the bottom is high. Therefore, very little of the deep sea has been explored. In fact, barely five percent of the ocean’s depths have been explored by humans. Researchers also know less than they would like about the organisms that can live in the deep sea. Moreover, they cannot be brought up and studied in aquariums or laboratories because they are adapted to withstand the high pressure in the depths of the sea.
To live in the depths of the oceans, where light does not reach, animals must adapt to life in darkness. Many have large mouths, light organs, or large and extra light-sensitive eyes. There is also a diversity of microorganisms living in this challenging environment. The fact that life can exist under such extreme conditions without oxygen or sunlight has led researchers to consider that there might be life on other planets that we have previously thought to be lifeless.
Although we still know very little about the organisms of the deep, it is known that overfishing and bottom trawling can also affect deep-sea animals. Many organisms are still undiscovered and therefore at risk of disappearing if fishing continues as it has done so far.
The Mariana Trench in the Pacific Ocean is the world’s deepest place in the sea. The maximum depth is Challenger Deep, which is approximately eleven kilometers below the sea surface. At the same time, the average depth of the world’s oceans is about 3700 meters. Sweden’s deepest point is 560 meters in Bratten in Skagerrak, and the Baltic Sea’s deepest point, Landsort Deep at 459 meters, is west of Gotland.
Ecosystem services
The world’s oceans and seas are a significant asset for us humans. The oceans provide us with a multitude of services. To remind us of the importance of the oceans and the need to protect them, June 8th has been designated as World Oceans Day by the United Nations. But there are more reminders of how important the ocean is in our daily lives.
World oceans give us more than just food. They produce more than half of all the oxygen in the atmosphere through photosynthesis, absorb greenhouse gases, and contribute to tourism. Some well-visited tourist destinations at sea include Gotland, the Koster Islands, and other archipelago areas.
Additionally, hundreds of millions of people depend on fish and other resources from the sea. More than 38 million people are employed in the fishing industry worldwide. The oceans are also widely used as transportation routes.
Coastal ecosystems such as coral reefs, seagrass beds, and mangrove forests are crucial places for the young. They are also significant for people living on the coast as they act as a protection zone against floods, storms, and can serve as wave breakers and erosion protection.
TEXT: Lina Mattsson
An exploration of the motivations and methods behind China’s growth and control over fishing across most of the high seas.
The endangered irrawaddy dolphin species has increased to over 100 in Cambodia, according to the country's Minister of Agriculture, Dith Tina.
Daniel: The tragic tale of an Indonesian deckhand and his brutal voyage on a Chinese squid ship.
The Chinese fishing fleet is a great power on the sea. It fishes far out to sea where no country's laws reach, and it fishes more than any other nation right now. And it does so at a terrible human cost.
China uses thousands of workers from the Hermit Kingdom, in violation of U.N. sanctions and U.S. law. Many at the plants recounted rampant sexual abuse.
China forces minorities from Xinjiang to work in industries around the country. As it turns out, this includes processing much of the seafood sent to America and Europe.
An exploration of the motivations and methods behind China's growth and control overfishing across most of the high seas.
Maybe an odd job even for the accomplished South African free diver Nick Filmalter, but he became an essential part of ensuring the safety of our divers during the shooting of a documentary about the Sardine Run, in South Africa. He was the guy chasing away the sharks which became more interested in the crew than the sardines!
The disappearance of Great White Sharks from False Bay, South Africa, attributed to various factors including predation by orcas, human activities such as longlining fishing targeting their prey, and the resulting decline in the shark population. The Shark Spotters team, responsible for monitoring the bay's waters, confirms the absence of Great Whites since 2019 and points to orcas as a contributing factor.
Dive into the intricate ecosystems of the world's oceans, their lawless stretches, and the extremities that teem with life, all crucial to our existence and well-being.
China accuses the US of raising tensions The United States is "creating tensions" in the South China Sea by allowing a US warship to travel through shipping lanes claimed by Beijing, China claims.
It is the world's longest submerged tunnel of its kind and will halve the travel time from Skåne to the continent. But a legendary Swedish naval victory in 1644 was setting the stage for the gigantic tunnel construction in the Fehmarn belt.
There are more than 400 species of fish being farmed globally. Most of them spend their entire lives in barren conditions. It’s a lifelong suffering.
Across the world scientists and biologists are studying a huge variety of dedicated and intricate subjects: jellyfish proteins; fish intelligence and whether octopus dream. On the other side of the coin are the naturalists
I was really happy with my task, staying on the surface. I truly wanted to snorkel with dolphins, but the sharks made me hesitate. Finally, Joel convinced me to join him. It was so cool to see everything from below, and I finally got to snorkel with dolphins! But it was the whales that made this day unforgettable.
In the midst of the chaos of sardines, dolphins, birds and sharks there appeared a lonesome Humpback whale. She seemed not to be concerned with the frenzy which ensued around her but rather quite intrigued by the shoal of sardines which seeked refuse under her enormous shadow.
The play unfolds right in front of my camera - my breathing rate is high. Nick and Kimmo are with me. We spread out so as not to ruin each other's shots. Nick was supposed to be our "safety diver," but we don't have time for that now. He has to film too. When the opportunity arises, we must seize it!
In southern Portugal, a group of passionate divers has deliberately sunk four large marine vessels, not only to enhance the diving experience but also to foster new habitats for marine life.
He has been seen in several places along the Swedish coast in recent days, but suddenly the alleged spy whale Hvaldimir appeard in the middle of Gothenburg's harbor.
A white whale has been branded a Russian spy. If that is true, only Russia knows. But there is a long history of using marine mammals for military missions around the world – as mine detectors, sentries and submarine hunters.
The narwhal is a relatively small arctic toothed whale (4 - 5 meters). It is shy and typically lives in the drift ice around the northern ice cap, where it can live up to 100 years. This makes the narwhal particularly vulnerable to the severe climate changes that are taking place around the Arctic. The Inuit have traditionally hunted narwhals both for their valuable tusk, fine meat and not least, for the tasty skin.
There is a treasure hunt going on in the deep sea. But among the rare minerals on the bottom, scientists have also discovered about 5,000 completely new species of sea animals.
On December 14th, 1991, the passenger ship Salem Express sank when a storm hit the Red Sea. The shipwreck was a human tragedy. Among the passengers were hundreds of pilgrims who were on their way home from Mecca.
The 11th of February is the UN’s International Day of Women and Girls in Science.
