Step 1
Create a document and fill it with a light gray background.
Step 2
Goto Filter>>Render>>Difference Clouds. Press Ctrl+Alt+U and move the saturation bar all the way to the left at -100.
Step 3
Goto Filter>>Sketch>>Chrome Set Detail to 10 and Smoothness to 0. Create a new layer over this and fill it with blue. Set the blending mode to Color. You now have blue water.
Final Result:
More Tutorials: 
