Lin had gotten in over her head. She actually looked somewhat like Undyne right now, but she wasn't a fish person naturally. The pressure WAS getting to her down here, AND she didn't actually know how to swim. She had a flashlight hanging from a lanyard around her wrist to provide enough light as she slowly climbed up the rocky wall of The Gap.

When she glanced to the side and saw a single, glowing eye in the darkness she let out a yelp and almost lost her grip. On the surface, she would have felt confident she could defend herself. Down here, she was feeling a lot more insecure. "S-stay back! I'm not tasty at all!"