The sandy shoals covered permanently with a low layer of sea water represent the 'youngest' land in the Danube's Delta.
They are created by the continuous deposition of sediments, carried by the Danube and layed in the areas where it flows into the sea.
This phenomenon is manifested due to the fact that, in time, the gulfs clog and allow the birth of islands. The most known example is the Sacalin Island.
The shoals are covered with a layer of brackish water, a mixture of salty sea water and fresh water brought by the Danube. This layer of water has 20 to 30 cm in depth.
The sandbanks represent an optimum habitat for numerous species of submerged (macrophyte) plants, which are adapted to brackish water.
These plants are a source of nourishment for the species of herbivore birds and a source of shelter for the brackish water fish.