She will head to the reception

Sophia just had to keep calm and everything would be fine. Her towel gave her plenty of cover and although it was unusual to go into the reception area in a towel or bathing suit, it would not seem to strange. Of course, she would be wearing nothing but a towel, but nobody should be able to tell.

If her guess was correct, her bikini was now in the lost-and-found box in the office behind the reception desk. To make it there, she would have to first go through the first door leading from the lockers into a short hallway, then through a second door into the very open reception area. She could then either simply ask the clerk for her stuff back or somehow sneak behind the desk and into the office unseen. The second door required a ticket to get through when coming towards the pool, but at least she could freely go through it going out. She would have been entirely trapped here otherwise.

Sophia did her best to act casual as she left through the first door. This brought her to the short hallway and then the second door. Looking through the window in this door, she could look into the reception area. There was a pair of girls about her age at the desk, but apart from them and the lady behind the desk it seems there was nobody else in the room. That said, the front of the building was almost entirely glass, giving an unobstructed view of the parking lot, the adjacent park, and surrounding buildings. Sneaking would be difficult, but she would have to queue behind the two girls in order to reach the clerk otherwise. That should not be a problem, although every second out there in nothing but her towel would be very awkward for her.