Archimedes' principle states that when a body is immersed fully or partially in a fluid, it experiences an upward force that is equal to the weight of the fluid dispersed by it.
There are various applications of Archimedes' principle. It is used in designing ships and submarines, lactometers and hydrometers are also based on this principle.
This principle is also used to find out the cavities. However, it can be different and vary according to the question. Kindly clarify your query so we can help you.