The fractional compression $\left( \frac{\Delta V}{V} \right)$ of water at the depth of 2.5 km below the sea level is $\underline{\hspace{2cm}}$ %. Given, the Bulk modulus of water =$2 \times 10^9$ N m $^{-2}$, density of water = $10^3$ kg m $^{-3}$, acceleration due to gravity $g = 10$ m s $^{-2}$.