Geliebte Diebin (Seven Moves to Checkmate) Underwater Scene

Bettina Zimmermann's character infiltrating a pool by swimming in through the valve. I always found this scene fascinating for whatever reason. I dunno, it might just be because I have to wonder how long it took to swim from the tank to the pool itself after being sealed in. She doesn't seem to have had difficulty holding her breath. I would've loved to see a view of her swimming through that passage, to know how long it actually was and to know if she ever came close to drowning.