Minecraft seed 3.1459 gives a beautiful world full of lakes, and a cave put into the side of a cliff.

Said cave goes from the surface, to bed rock.

I have found 7 Lapis Lazuli veins, shit tons of coal and iron, gold errywhere, naturally occurring water on lava goodness, diamonds, two dungeons, and eventually hit bedrock.

I only ever dug through gravel, and have found several wide, tall chambers.

Huge cave is huge.