Question

Why does a dead body float in water with its head immersed in water?

Answer 1

A dead body in water sinks when water enters into the lungs. Once submerged, the body stays underwater for sometime. Then there will be release of gases like methane, carbon dioxide and hydrogen sulphide  due to the bacteria present. Because of this the upper portion of the body (torso), which contains the most bacteria, bloats more than the head and limbs. The most buoyant body parts rise first, leaving the head and limbs behind. As the density of the head is more than that of water, it remains immersed in water.