I watched a timelapse video I captured from this same sunset event, and I think I happened to find the same moment and splash... blue sky, orange sun and sunlight, blue light on the shaded waves and white foam. What I find really interesting is that like in the image above, the splash has a mixture of direct faint orange light from the last bit of the sun, and the blue light from the sky, and the result is a more pink-magenta shade of orange.
This is a fairly unique case where nearly all of the sun's evolving influence is shooting through the narrow cave. A previous splash I caught just two photos earlier is much more orange. It's amazing how lighting from all different directions can affect areas of an image, and for how short a time some of these effects can be!