Hall of Infinite Doors by apotheosis R

You swim through the vast depths of the water, glad to note that your clothes don't seem to be holding you down. When you dive, you notice a hole and a passage leading forward. Luckily, it slopes upward, and so it's really easy for you to swim through it. You step out of the pool, and seem to exit through a similar archway elsewhere.

You're not really paying attention. The water is dripping over your eyes, and your wet clothes are making you shiver.