Rendering water in a pool in a few easy steps

[Ofnuts]

1) Filters>Render>Noise>Solid noise and increase the Y size to stretch the shapes horizontally

   

2) With the Curves tool, apply a curve made of 4 to 6 sines

   

   

3) Color>Map>Gradient map and map with a Dark blue to light blue gradient

   

[Espermaschine]

Now that Sinus has gone GEGL it has become a lot more fun.

   

[Ofnuts]

Not bad, but you have little control on the shape, you have to click "New seed" until you get something you like.

[Ofnuts]

Nice. How did you distort the text to match the waves?