The mouthpiece would not need to be in her mouth. As this is a work of fiction it is entirely plausible that a dolphin would retrieve her stage bottle upon seeing her without a reg in her mouth. A team of them would then turn on the stage. Purge the reg as it was being placed in her mouth and swim her away. unconscious doesn't mean she stopped breathing so it could happen that way. Seriously if the op wants to add some realism to her story and use actual facts it should be applauded. There are fins on ladders as well but they are not the norm if diving alone. A more plausible line is she was snorkeling and spotted something. Not knowing someone was on the boat. She came back to get her scuba gear that was already assembled from and earlier dive. Was getting geared up to do the dive to check out whatever and was hit. Fins would be on, air on, and possibly reg in her mouth. More suspenseful and more sinister as well. Would just need to set it up correctly. Not hard to do at all.
