An active stabilization device for stabilizing, for example, a vessel at sea, both in a first operating state in which the vessel moves and in a second operating state in which the vessel is in a rest position, includes at least one fin body (2) and a drive device which is connected to the fin body and is configured to drive the fin body. The device furthermore includes a hinge mechanism (5) which is connected to the fin body and is configured to position the fin body with respect to an outer side (1) of the construction by rotating the fin body about a first rotation axis 4 in such a manner that the fin body can generate a lifting force which can stabilize the construction at least in the second operating state. A vessel at sea which includes the device is also described.