Dolphins

Let's start with underwater background. The easiest way to draw it is radial gradient. Set foreground color to lighter blue and background color to darker blue. Select Gradient tool, then select Radial on toolbar, then draw gradient from top-center of image to right-bottom (or left-bottom).

I used wonderful photo by Leandro Stanzani as a reference for my drawing. Locate the photo inside your image...

..and set its layer opacity to 15-25%.

Set foreground color to lighter blue. Switch to Pen tool, create shape of big dolphin body, carefully outlining it from the photo.

In new layer, use Pen tool and make white shape of dolphin's belly. Set layer opacity to 10-20%...

... then Create Clipping Mask (Ctrl-Shift-G or from Layer menu), so that shape of belly is limited by shape of dolphin.

In new layer, use combination of large and small soft brush (black and white) to draw lightlights and shadows.

Set layer mode to Overlay and Create clipping mask again (Ctrl-Shift-G or from Layer menu).

I decided I wanted to have edges a bit mor glowing, so I used small soft white brush to outline the edges (in new layer)...

...then set layer opacity to Overlay and Create clipping mask again.

Zoom in, set foreground color to dark blue, switch to Pen tool, carefully draw shape of mouth.

Switch to Brush tool, with small soft white brush, add some highlight...

... then - you guessed! - set layer mode to Overlay, and Create clipping mask.

... in new layer, with Pen tool, add an eyebrow shape (as always, layer blend mode = Overlay, opacity - to your liking).

Switch to Pen tool. Using the same color as body shape, create shape of a fin.

Create a layer mask (Layer menu - Layer mask - Reveal all). Switch to Brush tool, set color to Black, use black brush to remove unnecessary part of fin.

In new layer, with white and black brush, draw highlights and shadows.

... as always, Create clipping mask...

Set layer blend mode to Overlay, then adjust layer opacity carefully, until the top line of fin is the same lightness as dolphin body.

Small but important detail - use dark blue soft brush to add a shadow (in new layer under layer with fin shape).

Under layer with dolphin body shape, use Pen tool to draw another fin (with dark blue color).

This dolphin is ready! Using the same techniques, create a dolphin child. The instructions are the same, so I'm only show the screenshots...

Create new layer between layers with Dolphin and Dolphin child. Use very large black soft brush to draw shadow that falls on dolphin body. Make sure shadow is inside body shape - use Eraser tool to remove brush outside body.

Set layer blend mode to Overlay or Soft light. Adjust opacity to your liking.

The dolphins are ready! The final detail I added was bubbles, but you should already know how to do them from my previous tutorials :-) Thanks for reading!