In order to determine the depth in the ocean, use the following equation:

h: depth
P: pressure = 3*Po
Po: atmospheric pressure = 1.013*10^5Pa
g: gravitational acceleration constant = 9.8m/s^2
p: density of water = 1025 kg/m^3
Replace the previoua values into the formula for h and simplify:

Hence, the depth in the ocean is approximately 20.17m