Puppy Ray in PD Howler 11 adds a water plane, with waves, and refraction.
Here's an example:
Here's a comparision of 3 renderings of the same scene.
Rendering in Puppy Ray, without the water plane.
New in v11: improved rendering quality.
New in PD Howler 11 - enable the water plane,
with waves to reflect the mountains and sky.
Also new in PD Howler 11 - enable transparency
with refraction on the water plane.
Note that the above image was rendered with an early beta version that
was not yet calculating reflections in floating Point precision.
The Sun's reflection was reduced in intensity as a result of it. The final version is much better with that regard.
A few more:
And here are even more, in a slideshow video on YouTube:
RefracTest - a few tests with Puppy Ray's refractive water plane