The open ocean is enormous. Also called the pelagic zone, it includes all the world’s oceans except for coastal waters and the sea floor.
Pelagic waters are not all the same. Some areas are teeming with life, while others are nearly lifeless. Enormously long currents flow like rivers under the surface, influencing everything from the concentration of marine life to weather systems on land. There’s also a huge 'vertical' variety, from sunlit surface waters down through the twilight zone to almost complete darkness and crushing pressures below 1,000m.
Despite its vastness, only around 10% of all marine species live in the open ocean. But these include the world’s biggest, fastest, deepest diving, furthest travelling ... and, to our eyes, most alien-looking animals. And some of these are of immense commercial value to people.
Only a narrow coastal strip of ocean falls within the territories and Exclusive Economic Zones (EEZs) of coastal countries. The estimated 64% of the oceans lying beyond such coastal waters are known as the High Seas.
Covering over half the Earth’s surface and making up 80% of its living space, or biosphere, these open ocean and deep sea environments are some of the least-explored areas on the planet.
The High Seas are international waters, meaning they are open-access common areas for everyone. Although various international and regional agreements have been established for High Seas use, many activities are not restricted. There are few regulations for commercial fishing, oil and gas exploration, mining, shipping, bioprospecting, and pollution on the High Seas - and even where regulations do exist, there are few nations that will enforce them.
As a result, many High Seas areas have already become degraded. New management regimes are required to protect High Seas species and habitats while allowing for sustainable resource use.