Good luck?

This is not really my photo, is my mom's.  We where together at Avellanas beach. I was shooting at surfers, camera in tripod, all settings ready.  She wanted to shoot too, so I left her the camera and went into the ocean. She shot for about an hour. It was the end of the day, so the light started to change fast, the sunset came, low light conditions appeared, and my mom just kept shooting without changing the settings.  Despite she is a passionate amateur photographer, she doesn't know how to work the settings.  The fact that she didn't adjust for low light to freeze the surfers,  resulted into this moved photo.  What normally would be a mistake in this case created a very interesting image.