The ocean

The ocean covers approximately 360 million square kilometres, about 71% of the Earth’s surface. It contains 97% of the Earth’s water, which comes to roughly 1.35 billion cubic kilometres of water. The average depth of the ocean is 3,688 metres, its deepest point is at 10,983 metres.

95% of the ocean has yet to be explored, 91% of ocean species to be classified and 75% of the ocean floor to be mapped at high definition. Scientists estimate that the species diversity of the ocean lies between 1 and 2 million species, with millions more bacteria, other microbes and viruses.

Ocean habitats vary dramatically, from tropical coral reefs to the freezing poles, from mangroves to the deep sea; each habitat is shaped by its range of light, temperature, depth, pressure and salinity.

The ocean never rests, its movement stems from the Earth’s rotation, tides, wind, temperature and salinity. Watch this visualization of ocean movement based on data collected during field observations and by NASA satellites to see how this looks.

Ocean water temperature ranges from 30ºC at the surface to -1ºC at the ocean floor. It can reach up to 400ºC at hydrothermal vents, where the intense pressure at these depths keeps the water from boiling.

Its importance

The ocean produces between 50 and 80% of the planet’s oxygen, absorbs over 90% of the excess heat caused by climate change and takes up about 23% of carbon dioxide emissions.

If the ocean were a national economy, it would be the seventh largest in the world, the OECD estimates that the annual market value of all marine and coastal resources and industries will reach US$ 3 trillion by 2030. Already back in 2015, the World Wildlife Fund for Nature’s report Reviving the Ocean Economy: The case for action—2015 estimated ocean resources to be worth US$ 24 trillion.

More than 3 billion people rely on the ocean for their livelihoods and more than 350 million jobs are linked to it. Nearly 2.4 billion people, about 40% of the world’s population, live within 100 km of the coast.

97% of our communications are carried via more than 400 submarine cables extending over 1.2 million kilometres in length. 90% of goods are transported by a fleet of just under 100,000 ships of 100 gross tons or more, registered in over 150 nations, crewed by over a million seafarers, and carrying cargo all over the world. Ocean-related tourism, from surfing to restaurants, hotels to cruise ships, accounts for more than 80% of tourism and is growing at an estimated € 114 billion a year.

Our impact

The ocean is heavily affected by humankind: climate change is heating the ocean, causing sea levels to rise, melting polar ice, killing coral reefs, increasing levels of acidification and storm intensity and causing more frequent marine heatwaves; over-exploitation and destructive fishing practices are crippling fish stocks and destroying deep-sea ecosystems while the shipping and extraction industries both pollute the ocean environment and harm marine life.

Each year around 11 million tonnes of pollution enter the ocean from land-based activities or from ships. Whether plastic, runoff, oil or discarded fishing nets, the ocean is fighting a losing battle against anthropogenic waste, the number of dead zones is on the rise and marine life is being stifled. Plastic waste kills up to 1 million seabirds, 100,000 sea mammals and marine turtles and countless fish each year.

We have chosen to ignore our impact on ocean ecosystems and marine life for too long. Now is the time to turn this round and to stand up for the ocean, not just for its protection but also for its restoration.