There are couple of places in caves where, the cave stop rendering if looked at from a specific position, Instead, the sky is shown. See the screenshots. The caves in the distance do not render in the first screenshot, taking two steps left, they render, taking two steps right they stop rendering again.
Graphics: Nvidia GeForce 480GTX in 2-way SLI configuration.
World Seed 818010429
/tp 993 23 -83