Why is chest of an face diver compress for an increase in atmospheric pressure

Boyle's Law states that for a fixed amount of gas at constant temperature, the pressure and volume are inversely proportional.

where $P_1$ and $V_1$ are the initial pressure and volume, and $P_2$ and $V_2$ are the final pressure and volume.

As a diver descends, the ambient pressure ($P$) increases. To maintain the equality in Boyle's Law, the volume ($V$) of the gas in the lungs must decrease proportionally.

The air in the diver's lungs is compressed to a smaller volume. This reduction in lung volume causes the chest cavity to be compressed inwards by the external water pressure. The deeper the diver goes, the greater the pressure, and the more the lung volume decreases, leading to a more pronounced compression of the chest.