Step 1.
Import image effects to your project.
Step 2.
Add the components Vortex, Vignette and chromatic aberration, blur optimized and audio source to your camera.
Step 3.
Add the water effects script to your camera.
Step 4.
Drag the water object from the hierarchy to the Water prefab section in the water effect script.
Step 5.
Add a custom underwater sound to the audio source (not required) *Put audio source on "Loop"*
Step 6.
Enjoy :)