In the 'night swim short story', perhaps the setting of the night swim is used to create a certain mood. For example, the darkness of the night could add an element of danger or adventure. The protagonist may have some self - discovery during this night swim, like facing their fears of the unknown in the water.
One possible main theme could be adventure. Night swimming is not a common activity and often comes with a sense of the unknown, which can lead to an adventure - like plot.
No, Night Swim isn't based on a true story. It's a work of fiction that was made up to entertain and engage readers, without drawing from actual events or individuals.