Suppose sea water has a density of . The buoyant force of the sea water is equals to the weight of seawater that the diver displaces in 0.061 m3 volume
So the mass of seawater he displaces is
As the diver's mass is 64.1 kg which is larger than the mass of seawater displaced, so as the weights. Therefore the diver will sink.
In physics and engineering, a free body diagram (force diagram, or FBD) is a graphical illustration used to visualize the applied forces, moments, and resulting reactions on a body in a given condition.