Wow,
short and effective. I searched for something like that for a long time!

Step 1

Step 2
We need to make a gradual change between a lighter shade of blue and a darker shade, so select values similar to these.

Step 3
The gradient tool should be selected, and select a LINEAR GRADIENT.

Step 4
Starting at the top, click the mouse, and holding SHIFT drag it down to the bottom, this makes the gradient stay in a straight line, avoiding funky semi-diagonal gradients.

Step 5
Now we're making a new layer, i always recommend naming layers, just so that images with more layers don;t get so confusing.

Step 6

Step 7
Make sure that your foreground and background colours are set to black and white, then select FILTER -> RENDER -> CLOUDS

Step 8

Step 9
Now hold CTRL + T to bring up the transformation box, and pull the image in from the bottom, to create a layer squashed near the top.

Step 10

Step 11
Now adjust the perspective by pulling one of the handles at the top to either side.

Step 12
Now add a layer mask, and set the layer mode to 'Colour Dodge'. You should also reduce the opacity to make the effect a little more subtle.

Step 13
now paint with a soft black brush on the layer mask, that makes the effect more gradual and more natural

Step 14

Step 15
The plastic wrap filter creates a three dimensional look, making it look like waves. Apply these values, or change them if you wish

Step 16
Now we create a sun, so go to FILTER -> RENDER -> LIGHTING EFFECTS. and apply the values shown on the right. Make sure the type is set to OMNI, that way it looks more like a sun.

Step 17
FILTER -> RENDER -> CLOUDS make sure black and white are your default colours

Step 18

Step 19
To change the BLUR CENTER just move your mouse over to the top and click, this is so that it seems like light is coming in from the top

Step 20

Step 21

Step 22
In this case, i applied the blur twice, to create a silkier effect

Step 23

Step 24

Step 25
by the top layer, i mean the layer the we named 'Top' earlier.

Step 26

Step 27

Step 28
And voila! You have your underwater image! Thank you for taking the time to read!

21 Comments:
nice tutorial, i remmeber back in the days at ost we had another underwater effect tut but i dont remember it TOO clearly, just we had some under water sources and as result someone came up with a tut
.
Your tut is very descriiptive and should be easy to use, just a tip, if you want to draw a circle arround something to point it out it may better work if you use red and a sharp brush and not a brush with soft edges.. just looks better
anyway nice tut thank you 
Thanks! I was working on layer masks quite a lot in the tutorial so the default colour was always black and i forgot to change it i guess, but thanks 
i work for adobe. work with photoshop everyday. and this is a really nice tut havent got the time to try it out but i will do it. Thanks for the nice tip 
its a cool effict ,thanks for nice tutorial
(210 days ago)Not many tutorials i do work, but this one worked perfect! Thanks
(208 days ago)This sucks i have been working on this for an hour now and i cant get it your instrucitons suck thanks for wasting my time.
(207 days ago)To the previous guest who did not care for your "instrucitons" -- you wasted our time reading your ungrateful post. It takes a lot of preparation and time to write a tutorial and this was one of the best. I'm a beginner and it was easy to follow, and I sincerely appreciate designers who are so willing to share their knowledge. Kudos!
(207 days ago)Thanks for this!Mine worked just fine & your instructions were easy to follow!
(206 days ago)this is awesome man 
aMAZING TUTORIAL dEDICATE MORE TIME INTO KNOWLEDGE.
(199 days ago)Great man....Many thanks
(191 days ago)wow ! excellent.
kavi
great tutorial! simple and to the point. Thank you!
(172 days ago)simple and very effective
(172 days ago)o thats cool xD
(167 days ago)Im having a problem I cant follow step 13 and it is disturbing the whole work
how to do it perfectly
Guest, you simply add a layer mask on that layer, or if you are using elements and do not have a layer mask, simply erase part at the bottom with a soft brush.
(112 days ago)brilliant v.good liking it!
(95 days ago)thanks.. very simple ...
(87 days ago)
vp: 2832
rep: 43.3
Very clearly written with a nice result
(222 days ago)