You continue following your journey, and suddenly you notice a laboratory up ahead. Going further, you arrive at the laboratory, and when you approach the door it opens automatically

Entering the laboratory, you hear a machine noise, and decide to get closer and hide behind a cabinet to try to see, and when you realize it, There was a fish woman working there, but you accidentally made noise

"Swap Undyne: Uh..Who's there?"

She seemed to be looking in the direction where you were hiding.