Hmm, unfortunately I have no suggestions. The only one I've seen that actually falls into that category is SAO, which seems to be a staple anime (even though I'm not a fan, but that's okay).
Oh! Maybe Gantz would count? I've still only seen a couple of episodes though, I need to finish it one day! Hopefully before 2018 haha
And I know this doesn't really fall into "trapped in another world" but....
Texhnolyze features mostly the underground and the surface is like a whole other world, which is apparent when they eventually go to it.