Step 1
Open up a 500(width) by 350(height) white document.
Step 2
Select your gradient tool, and set your foreground colour as 1a687b, and your background colour as 10a6c1. Once you have the colours in your colour palette, create your underwater background by starting from the BOTTOM, and clicking and dragging your gradient tool to the top. The end result should look like this.
Step 3
Select the 'Text Tool' and type in the text you want to use. In this tutorial, I have chosen the font "Impact" at the size of "72" and white as my text colour. So now you have a gradient background, and some sort of text in the middle of your document.
Step 4
Right click on your text layer, and goto Blending Options. Be sure to use all the settings below for accurate results.
Step 5
With all those blending options activated, your text should now look like this.
Step 6
I added a couple of bubbles to enhance the look, and also a slight reflection. And this is what I came up with.
More Tutorials: 
