Underwater Wallpaper Effects

Then, simply set the blend mode of this layer to Overlay. Voila!

Next step is some bubbles. Select 19px hard brush, and set its spacing to very large value (500-700%).

Also, check Shape Dynamics, and set size jitter and minimum diameter as shown here.

Make some chaotic btush strokes.

Set layer blend mode to screen (this will make black dots invisible). Then, use layer effects (such as inner glow, drop shadow, bevel and emboss) to make dots look like bubbles. Registered users can download PSD file from Downloads page of my site, and see what exactly effects are used.