Abstract: A support device for cultivating macro organisms in marine waters consisting of first and second coplanar rings connected to each other by a plurality of radial support lines and provided between them with a plurality of cultivating lines arranged in substantially coaxial rings and connected to the support lines. The outer one of the first and second rings is held in a predetermined orientation by ropes of crow's foot arrangements connected to it from above and below the rings. Each crow's foot arrangement is provided with a ring coaxial with respect to the first and second rings and connected to the other by a support rope. One of the crow's foot rings is connected to a buoyancy means and the other one is connected to an anchoring device so that forces acting on the buoyancy or anchoring means are restricted to the support rope.