If you're trying to create a simple tropical ocean with a simple beach you can try using this tutorial.
You'll need to know your way around Photoshop. I don't explain everything in detail. I created this one in a couple of minutes, so the text and image quality isn't the best, but hopefully you'll understand and have the skills enough to create something much better out of it.

------ Simple Ocean Tutorial by lassekongo83 ------

1. Start by creating a gradient sky with your colors of choise. Create a new layer called beach. Draw the beach with a normal brush tool. Smudge out the sharp edges with the smudge tool.

2. Create a new layer called ocean. Draw it with a normal brush. Add some extra darker blue colors on it. Draw some small-medium lines with the beach color where the beach meets the ocean. Smudge around with the smudge tool again.

3. Get yourself a texture of waves. Easiest way to do this is to create a simple ocean in Terragen, Vue or Bryce. Put it over the ocean layer. Set the layer style to Soft Light and the opacity to around 35%. Erase any sharp edges with the erase tool.

4. Create a new layer above all the others. Draw some simple white lines where the beach meets the ocean. Smudge it out a bit until the edges looks soft and ok.

5. Finish your image by merging the ocean and wave layer. Erase the messy top and soften the horizon a little bit.

6. Image is still far from finished. Mix around with different lights, objects and whatever you feel like.