Furthermore, the buoyant force acts through the center of buoyancy, which is the centroid (center) of the immersed part of the object - this is the volume of water that is displaced by the object. For the object to maintain its orientation in the water (i.e. not rotate) this buoyant force must pass through the center of mass of the object. If this buoyant force does not pass through the center of mass, and is offset from it as shown in the figure below [1], then the object will rotate until the buoyant force passes through the center of mass. At this point rotational equilibrium is reached. In the figure below the buoyant force acts at a point that is to the right of the center of mass and as a result will cause the swimmer to rotate counterclockwise.
In addition to eventually reaching rotational equilbrium, an object floating in water will eventually also reach translational equilbrium. This is when the upward buoyant force acting on the object is equal to the weight of the object. When both of these conditions for equilibrium are reached the object stays stationary. An object that is in equilbrium will always satisfy both translational equilibrium and rotational equibrium.