Open the file "Boat". Copy/paste the boat into our scene and place it near the island.
Create a Curves Adjustment Layer and clip it to the boat layer. Use the settings shown below to lower the brightness of the boat.
Create a new layer and use the standard chalk brush to paint a rope connecting the boat to the island.
The boat (like the island and the rock) is submerged in the water. Draw some loose white lines where it makes contact with the water to simulate the waves crashing into it.
Open the file "Girl". Make a selection of the girl with the Pen Tool and copy/paste her in our scene. Place the girl just above the dragon's mouth. Use a layer mask to partially hide the bottom region of the girl where it is submerged underwater.
Choose the Bubble brush and paint some subtle bubbles around her leg. Select the standard chalk brush (at 20% Opacity) and paint some splashes around her.
Open the file "Hand". Make a selection of the hand with the Pen Tool and copy/paste in our scene. Move this layer below the girl layer and position it as shown below.
Create a Curves Adjustment Layer and clip it to the hand layer. Drag the curve down to darken.
Make a new layer and set the blending mode to Overlay. Clip it to the hand layer and paint with a white brush at 10% opacity over the tip of the hand and with black over the base of the hand to set some basic lighting.
Group all the hand layers together and duplicate the group (Ctrl + J). Put the group above the girl layer in the layer palette and position it as shown below. Add a layer mask and hide partially the base of the hand.
It's time to add the final effects to our scene. Create a new layer and fill it with a light blue color (#377672). Change the blending mode to Soft Light and use a layer mask to restrict the effect only to the underwater region of the scene.
Create a Color Balance Adjustment Layer (Layer > New Adjustment Layer > Color Balance) and use the settings shown below to add some warm colors.
Create a Curves Adjustment Layer and drag the curve down to darken. Fill the layer mask with black and paint with white only over the upper region of the sky to reveal the effect there.
Create a Curves Adjustment Layer and use the settings shown below to boost the green colors. Select the Gradient Tool (G) and shift-drag in the layer mask (from top to bottom) to gradually hide the green effect from the sky.
Press Ctrl + Shift + Alt + E to create a layer from all the visible layers. Apply a 15px Gaussian Blur (Filter > Blur > Gaussian Blur) and change the blending mode of this layer to Soft Light. Lower the opacity to 15%. You can see we slightly increase the contrast and achieve a somewhat dreamy effect.
Press Ctrl + Shift + Alt + E again to create another layer from all the visible layers but this time apply a sharpening effect (Filter > Sharpen > Unsharp Mask).
This scene look quite good already but the colors are still a bit desaturated. Create a new Photo Filter Adjustment Layer (Layer > New Adjustment Layer > Photo Filter) and use the settings shown below to boost the colors and unify them at the same time.