Some weird teleport stone port points, gets you stuck underground when you port to them:
http://imgur.com/a/VR74iI dunno if it's a fixable bug, but I wouldn't wanna run out of stones/ town port and be stuck there
Notes: The pics are out of order for some reason, but they get the idea across; the points don't show up unless you hover over them
PS: I've heard about the Solstice Outpost and about how it's only supposed to be in the Chinese version, but I haven't seen the stuck in ground glitch from porting to it