" I've been playing Minecraft for about 5 hours now. I dug myself a nice base in a mountainside made of stone, and ever since I've been mining and mining and mining. I've gone pretty far down and to the side. But I have yet to come across a preexsisting cave system. Is this normal? "

Yup, completely normal.  Sometimes you won't find them easily, other times you'll be directly over a vast network that never ends.  In addition to listening, you can also use the cartographer to find where they are.

Then set the difficulty to Peaceful.

" ....But I dont wanna run into baddies.... "

" @CraigAA said:

" ....But I dont wanna run into baddies.... "

That is why you listen. Plus they are not hard to kill.  "

" @The_Laughing_Man said:

" @CraigAA said:

" ....But I dont wanna run into baddies.... "

That is why you listen. Plus they are not hard to kill.  "

Also, the only ones you really have to worry about are the skeletons.  But even they are fairly easy, as long as you have room to strafe. "

" @The_Laughing_Man: Nah. All the REAL men play in hard mode. Either way, I find that the main thing that kills me are careless walks next to lava and digging straight down, breaking through the top of a gigantic cavern.  My first dungeon experience: Got there with one heart and no weapons, pickaxes, etc. I had been looking for my body where I died last time, but apparently if you die near a dungeon you don't get anything back. So I'm down there with nothing but blocks of dirt and stone, chipping my way around the top of the dungeon. I very carefully chip away key blocks, lure all the zombies to one side, then systematically start placing gravel behind them, each piece stacking on eachother, creating a wall. After about ten minutes I finally accomplish a complete zombie blockade. I make my way to the other side and drop down. I open the chest. A loaf of bread, one spider string, and an apple or something. Most discouraging thing on the planet. "

What the hell is it with this game? I don't get it??? 
 
Can someone explain why I want to play this game?

" What the hell is it with this game? I don't get it???  Can someone explain why I want to play this game? "