I've been playing the mobile version of Minecraft for a few days now, and have yet to see an underground cave system. Are there any generated with the terrain, or is it all solid ground?
I've spent the better part of an hour now searching for a source to confirm my answer, but I can't find anything. However with that said:
It's based on Minecraft Classic, so I doubt there would be, especially considering the world has an end just like the original Minecraft Classic on PC (on which there are no caves).
Add that to the fact that I'm yet to come across a cave system as well and I'm pretty sure there aren't any.
There are some seeds that you can use to simulate "caves" – they're not actual generated caves, more like base-less mountains or deep overhangs. Three I know are
Waterworld, but there are lots more.
I know some cave seeds, such as "BBB", "thegobsofbog", and "nyan". Most worlds have a chance of having caves though; just mine it out a lot.
They are adding caves in 0.9.0 so currently there are no caves But you can get big overhangs which look like caves i have a seed with it and here's the Seed-3939373 And here's a screenshot