When walking through the world occasionally in either the bottom right corner or the bottom left corner of the screen you can see through the world.
It just flashes up and then disappears again, however, if you stand in the right spot you can keep it up on the screen.

The pictures below show the issue, you can see through the world and can kind of see some caves through it. The picture where the error appears more white is with VBOs ON and when I turned off VBOs it appears blue.

I'm not to sure what this issue is as it isn't really similar to unloaded chunk issues I have experienced in the past. Also this issue has only started occurring on the latest snapshot, so the recent changes in the way the world loads and is rendered is probably the reason for this bug.