Here’s a free tutorial on creating a reflection in the water using Photoshop’s Transform tools and the Wave filter
Drag the Background layer on to the Create a new layer button to create a duplicate of the main image.
Press Ctrl/Cmd+T to activate the Free Transform controls. Ctrl/right-click inside the Transform box and select Flip Vertical.
Lower the layer’s Opacity down to 20% to reveal the image below. Place and rotate the reflection into place. Use Free Transform to rotate the reflection if you need to, to line it up with the existing horizon.
Once the reflection is in place, add a layer mask. Now you can use the Brush tool set to black to paint away the parts of the image above the horizon.
Increase the Opacity of the layer up to 70% and then set its blend mode to Soft Light. This will help merge the two together.
Add the Wave filter from the Distort options in the Filter menu. Keep slider values low, setting Scale to around 10. This will depend on the resolution of the image, however. Hit OK and this should complete the effect.