You can easily create the sun's rays shining underwater for a special effect. This can be done with Gradients and Layers. It can be done in any version of Photoshop. So here we go.
In the Layers/Channels/Paths pallete notice that the New White Layer is shown as Background.
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Step 2 : Press CTRL+SHIFT+N and the New Layer dialogue box opens. Click ok.
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In the Layers/Channels/Paths pallete you will find the New Layer as Layer 1 above the Background.
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Step 3 : Click the Foreground Color which is Black by deafult.
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The Color Picker opens.
Step 4 : To change the Foreground Color to a particular shade of Blue enter 1680D1 where the red arrow points to. Click ok. The Foreground Color has been selected.
The Foreground Color changes to the selected shade of Blue.
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Step 5 : Now click the Background Color which is White by default.
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Step 6 : Now enter 0C1B6C in the box shown by the red arrow. Click ok.
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The Foreground Color changes to the shade I picked.
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Step 7 : Click the Gradient Tool.
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Step 8 : In the top panel click where the red arrow points to.
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Step 9 : The Gradient Editor opens. The Gradient chosen is shown by the small white hand. Click ok.
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Step 10 : In the top panel click on Linear Gradient shown by the red arrow.
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Step 11 : Drag from top to bottom with Gradient Tool.
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This is the effect I have got.
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Step 12 : Press CTRL+SHIFT+N to make another New Layer. Layer 2 forms in the Layers/Channels/Paths pallete.
Step 13 : Again click the Foreground Color.
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Step 14 : In the Color Picker enter B9DDF9. Click ok.
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The Foreground Color has changed to the color I picked.
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Step 15 : Again click where the red arrow points to bring up the Gradient Editor.
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Step 16 : The Gradient Editor opens. Click on the Gradient shown by the small white hand i.e. the second from top left. Click Ok.
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Step 17 : In the top panel click on the Radial Gradient -- the second one shown by the white arrow.
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Step 18 : Drag at an angle as shown with the Gradient Tool.
Step 19 : This is the effect you get.
Step 20 : CTRL+CLICK on the Layer thumbnail of Layer 2.
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You will immediately notice a selection form.
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Step 21 : Set the Foreground Color to B9DDF9 and Background Color to 0C1B6C as shown earlier.
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Step 22 : Go to Filter>Render>Clouds.
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Step 23 : Next press CTRL+D to deselect. This is effect I have got.
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Step 24 : Go to Filter>Artistic>Plastic Wrap.
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Step 25 : When the Plastic Wrap dialogue opens give the settings above.
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You will get this effect.
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Step 26 : Click on the Move Tool.
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Step 27 : You wil immediately notice a selection appear.
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Step 28 : Now press CTRL+T. Then with the Move Tool push up the bottom of the selection towards the top as shown.
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Step 30 : Click the Move Tool again. This dialogue box opens. Click Apply.
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Step 31 : Press CTRL+J on the keyboard and the layer is duplicated as Layer 2 Copy.
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Step 32 : Change the Blend Mode. To do this click where the red arrow points to. It will reveal a pop up. From the pop up click on Linear Light.
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Step 33 : Now reduce the Opacity to 50%.
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This is how the image looks.
Step 34 : Press CTRL+SHIFT+N to create another new layer i.e. Layer 3.
Step 35 : Click on the Foreground Color.
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Step 36 : Set the Foreground Color to 32F7E7. Click ok.
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Step 37 : Now drag down diagonallywith the the Gradient Tool.
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This is the effect I have got.
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Step 38 : Change the Blend Mode to Overlay and reduce the Opacity to 60%.
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This is the effect I have got.
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Step 40 : Press CTRL+SHIFT+N to create a New Layer. Layer 4 forms.
Step 41 : Bring up the Gradient Editor as shown and click on the Gradient as shown by the red arrow. Change the Gradient Type to Noise. Change the Smoothness to 100%. Do not click ok.
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Step 42 : Now change the Roughness to 100% and tick the Restrict Colors and Add Transparency check boxes. Now click ok.
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Step 43 : Click on the Angle gradient shown by the white arrow. The third from the left.
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Step 44 : Select the Gradient Tool and drag down diagonally as shown.
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This is the effect you will get.
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Step 45 : Now change the Blend Mode to Screen and reduce the Opacity to 20%
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This is the finished underwater effect.