Hello I’m working with a couple of friends on a MMO and I’m creating the main city some dungeons and some forests… I need to make some caves , i tried several things but can’t do it xD Anyone could tell me how to create caves? Ty! 
Do a search for caves as this has been brought up many times.
There’s an example of how to do this in this thread.
The package in that example no longer seems to work with Unity3 beta