We want the lines and the colors look smoother (characteristic for an underwater atmosphere) that is why we should merge down all the layers: Layer – Merge Visible (shift+ctrl+e), copy the new layer and blur it out a little, selecting the Gaussian Blur.

Underwater Dance

Change the layer's type on Darken.
The Crop Tool and Rectangular Tool may be useful in representing the picture's frame.

Underwater Dance

The illustration is finished!

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