What is the pressure in $atm$ on a swimmer $10\; m$ below the surface of a lake?

What would be the absolute pressure at a depth of $1 \,km$ below the ocean surface? [Given: density of water $\rho = 10^{3} \,kg/m^{3}$,$g = 10 \,m/s^{2}$,$1 \,atm = 1.01 \times 10^{5} \,N/m^{2}$]

$A$ barometer tube reads $75 \,cm$ of $Hg$. If the tube is gradually inclined at an angle of $30^{\circ}$ with the horizontal,keeping the open end in the mercury container,then find the length of the mercury column in the barometer tube in $cm$.

During blood transfusion,the needle is inserted into a vein where the gauge pressure is $2000 \; Pa$. At what height (in $m$) must the blood container be placed so that blood may just enter the vein? (Density of whole blood,$\rho = 1.06 \times 10^{3} \; kg \; m^{-3}$,$g = 9.8 \; m \; s^{-2}$)

$A$ swimming pool has a depth of $3 \,m$. The pressure at the bottom of the pool due to water alone is: (Density of water is $1000 \,kg \,m^{-3}$, Acceleration due to gravity $= 10 \,m \,s^{-2}$)

Why does an air bubble formed in water grow in size as it rises from the bottom to the surface? Explain.