Create a first layer of a medium-sized bubbles over the entire area of the working field. Brush "Underwater Bubble (scatter)" and "Flat Underwater Bubble (scatter)", Size: 70 - 150px, Opacity: 50%, color: white. Not just scatter them throughout. Try to make a variety of textures - bubbles congestion or lack thereof. Add filter "Gaussian Blur" (Filter > Blur > Gaussian Blur), set Radius: 2.0px. I have converted each layer with the bubbles in Smart Object but you don't need do this.

Make small bubbles near the spheres to create depth (Size: 35px, Opacity: 50 %). Apply to this layer filter "Gaussian Blur" with Radius: 5.0px. And add the last bubbles, large size on whole working area (Size: 900px, Opacity: 100%). Be careful and cautious with their location. If you want to undo your last action, use Cmd/Ctrl + Opt/Alt + Z or Edit > Undo. Add filter "Gaussian Blur" with Radius: 13.0px.

Step 20

All done with bubbles and we come to a very interesting part - creating color effects and color correction. At first I did lighting and darken the background to make the image clearer and deeper. Create a new nondestructive layer by using Cmd/Ctrl + Shift + N or go to Layer > New > Layer. In the dialog box, specify the following settings for the layer: Mode: Overlay, set checkbox on "Fill with Overlay-neutral color (50% gray)". Use the Burn Tool (O) for create shadow and Dodge Tool (O) to create a light, as shown in image below. The beauty of this layer is that you can create the perfect lighting, without fear of damaging the image.

Set Brush Tool (B) (Size: 1400px, Opacity: 100%, Hardness: 0%, Color: #fff200) and draw three large spots on a new layer: great in the middle, a little less in left side and only hand edge on right. Decrease layer Opacity to 67% Return to Gradient Tool (G). Set form: Linear gradient, preset "Foreground to Transparent" and color #00aeef (on a new layer). Draw a gradient from the bottom border of the document and up to 1/3 of the central sphere. Change layer Blending Mode to "Subtract".