Deep-sea bed

Deep-sea bed © JNCC

The deep sea begins at the edge of the continental shelf, which is usually at depths over 200m.  

Just like in shallower areas, there can be various kinds of deep-sea bed, including bedrock, limestone pavements, boulders, gravel, sand and mud. 

There are some unique deep-sea bed types too, including manganese nodules, in which minerals such as nickel and copper as well as manganese, build up like the rings of an onion around a shell fragment or other hard particle.  Past interest in mining these nodules has yet to lead to significant exploitation, due primarily to the expense of extracting the nodules from such great depths.

Unique biological seabeds include ‘bioherms’, which are mounds or reefs of rock formed from the remains of marine organisms, and embedded within mineral rock.

Living deep-sea reefs are formed by cold-water corals. They can extend for several kilometers and be more than 20m high.  Much of the deep-sea bed is barren and inhospitable, so the cold water coral reefs form oases, in which the number of different species can be three times as high as on the surrounding soft seabed. 

Large colonies of sponges can also be found in the deep-sea.

For the official habitat definition please see the documents listed below.


European distribution

Large areas of the Atlantic Ocean are deep-sea bed.  Areas of the Mediterranean Sea which are deeper than 200 metres, are included as deep-sea habitat, but the Baltic, being a shelf sea, is not.

Deep-sea bed fact


Official habitat definition

EUNIS habitat A6 Deep-sea bed


Further information


JNCC EUNIS habitat correlations table