Choose the mask itself:



And next apply the Gradient Tool (G) to draw the gradient on the layer. The top part of the layer became transparent as you may see on the picture below:



Next step includes finding in Internet an underwater scenery, as next picture shows it:



Using the Eraser Tool (E), we may cut out all the unnecessary elements, except the water’s surface.



Move this picture on our picture and place it on the top part of the original one.



Select after that the Brush Tool (B) with the color #669999 and the Opacity of 10%. The brush’s adjustments should be those indicated below:



Try to represent next a kind of hazy mist:



Create a new layer and apply on it the Pencil Tool (B) for drawing several lines, resembling the whirlwind. The color is still the same.