From Izanagi Online Wiki

Caves are much like fields in the sense that they too host a plethora of "monsters to bash and throats to slit." There are, however, a couple of characteristics that separate caves from fields:

  1. Caves have a closed ceiling, unlike the fields' open-sky environment. This considerably restricts the player's view over a large area.
  2. Caves usually only have one Entrance and one Exit thus limiting access to multiple areas (there are some exceptions).
  3. Caves usually provide pathways to most of the Boss Rooms in Izanagi; Boss-room portals are marked in red.