What is the ocean for? The ocean hosts 70% of the life on our planet, produces oxygen and is a sort of radiator: it regulates the climate and distributes heat. The sea has a strong influence on climate The heat stored in the sea is released into the atmosphere, triggering rains, storms, hurricanes... Most of the water that falls on the Earth is the result of the evaporation of the ocean in the tropics. Phytoplankton, algae, and aquatic plants absorb huge amounts of carbon dioxide, just like trees. Take two breaths: thank the Amazon forest and all the woodlands for the first, but the second breath of oxygen is given to you by the sea. While we’re at it, let's get used to using the singular: it’s true that the Atlantic Ocean, the Indian Ocean, and so on, is written on maps to name the areas of water that together cover more than 70% of the Earth's surface, but really there’s only one sea. The salt water covering our planet is a single whole, just like the air above our heads is a single whole. We don't call the portion of sky above the territory of a country Italian atmosphere or Argentine atmosphere, do we? We humans give a name to everything on the planet; as terrestrial, non-aquatic animals, we call our home Planet Earth – but it would be more correct to call it Planet Water. And here, slowly, life Life developed in the sea 3.6 billion years ago and only much later (just 400 million years ago!) the first arthropods, insects and then amphibians came out onto the land. All the territories we inhabit have been shaped by the sea. Very often, in the distant past, what are now fertile plains were once sea beds. The sea is home to an immense diversity of ecosystems and living species The ocean provides habitats for organisms of all kinds: from microorganisms to the great blue whale. Some areas of the sea are home to more life than on land, partly because the ocean has an average depth of 3,800 meters – so it makes sense that there’s more space in the water than on land. Long live diversity! So-called bony fish display six times more diversity than land mammals, for example, and at least two thirds of the planet's animal and plant species live in the sea. And who knows how many species we still have to discover! We have maps of the seabed that are less detailed than those we have for the Moon, and the abyss surely holds some surprises for us. The sea and humanity are strongly linked to each other It’s not just those who live near the sea or thanks to the sea (such as fishermen) – all human beings are linked to the ocean: it provides food, medicine, mineral resources, energy resources, commerce and jobs by transporting goods and people. Although many environmental concerns and protection policies have to do with fresh water quality and soil quality (mountains, cultivated areas, trees...), very little attention is paid to marine water quality. We constantly pollute it with indiscriminate dumping, we exterminate whales and plunder fish, shellfish and crustaceans without giving the species time to reproduce, and we’ve spilled so many tons of plastic into the sea that it’s difficult to find a marine animal without some plastic residue in its body. It’s time to take care of our Planet Water!