A tetrapods is a four armed concrete construction used for the construction of breakwaters. A typical tetrapods weighing between 15 and 25 tonnes. In breakwaters merged tetra pods into each other so that they get an overall strength that makes it difficult for the sea to move them.
Tetra Poder was developed in 1950 by Laboratoire Dauphinois d’Hydraulique in Grenoble in France and is used in many places in the world. In Norway, the tetrapod adopted in Berlevåg after half of Black Bull breakwater was razed in 1959.