Who believes that the northern Adriatic sea is only a monotonous extended of mud and sand is mistaken. It is very other. It hides of the full of rocks oases: “tegnue”, depth rich of a completely particular flora and a fauna, that  vegetable and animal organisms contribute to create and to transform. They are true natural “reef” developed in the last three or four thousand years, various from  tropical organisms because here the main builder organisms are not the madrepores,  but the red limestone seaweeds or coral seaweeds.  They are found to approximately trae miles in direction south-east from the port, between the 17 and 25 meters of depth. The underwater divers can appreciate the great variety of shapes of life that populate this depth, only in the Mediterranean sea. Particularly striking, for shapes and colors they are the  sponges, colonial ascidians and the anemones. The rocks swarm of brittle starfishes and crustaceans, from the small hermit crabs to the majestic lobsters. Between the fishes many tompot blennys, damselfishes, brown combers and largescaled scorpionfishes, congers and brown meagres. “Tegnue”, in Venetian dialect, means “held” or “withheld”. The name refers to the nets to train of the fishermen that they were torn because they met  with these rocks on the depth and they were already notes to the end of the “700 when Abbot Giuseppe Olivi, great personage of Chioggia, described this in detailed way in its work “Adriatic Zoologica”. The discovery of the naturalistic value of this habitat is recent, but agencies and institutions are working in order to safeguard these places only for their beauties and riches.