Here is the artifact:
Here is some clarifying information:
- This appears only at 480 units from the origin, and seems to get worse (to a point) as I move away.
- All water should have sand rendered behind it, but the sand should be occluded (since I will eventually be rendering the water semi-transparently).
Here is my guess:
This looks like z-fighting, but my issue with this hypothesis is that none of these polygons are co-planar.