Caverns Make Great Classrooms Probably the most prominent feature of a cavern is the darkness.
This plays a very important role in the way animals live in caverns and how they adapt to the environment. This is the area at the immediate cavern opening. This is the rest of the cavern beyond the twilight zone, where no amount of light ever penetrates. Each cavern will have a different distance for each zone, depending on how large the entrance is and the contours of the cavern. Some caverns may not be big enough to have a dark zone.