I went caving for the first time in what feels like forever and had some pretty terrible experiences. Everything was going well, but while building a bridge across a pool of lava a Creeper came from SOMEWHERE (seriously idk where it would have spawned, let alone wiggled its way to me) and blew me up. Miraculously I found my way back despite being pretty deep. Most of my stuff survived but a stack of torches and about 40 iron burned in the lava.
So I kept exploring, running into others; tunnels and such, eventually finding a huge natural cave system. I'm always super careful in these things, placing tons of torches and looking ahead. So I near the end of a waterfall and turn around to look around, then I see this!
My heart found its way to my throat when I saw it. After realizing I was safe I continued on around a bend that led above that Waterfall. There was water streaming down this passage as well so I began my careful ascension. Hardly one block up a Creeper kisses me from a hidden corner. The current must have wedged him into the corner pretty good because he didn't show any signs of being there until it was too late.
After dying and throwing a tantrum I found my way back AGAIN by another miracle. When I climbed the Waterfall I saw the Creeper was still locked in its watery prison. I continued onwards back to where I died...only to be met by another Creeper!! I ran like hell and it got caught on a single-block corner. I carefully moved in to hit it with my pickaxe and retreat; on the 4th hit it blew up and did 2 hearts of damage. My stuff was waiting for me just beyond it. So I was back where I died and I decided to try and climb up again. And you'll never guess...there was ANOTHER Creeper in the SAME spot, pulled into that corner by the current. It didn't blow up on me though because there was a Skeleton wedged there with it that knocked me back. Since I had recovered my stuff I managed to use my Bow to defeat them both.
There were no more Mobs as I slowly swam up the stream and lit the cavern. I found the source of the water, and I could see the SKY through it! The journey led me DIRECTLY below Spawn, and you can see the tunnel from the surface of the water.
So feel free to explore Creeper Cavern x_x