October Flash Fiction Prompt

We’re trying something new with this month’s Flash Fiction competition. Below you will find an image and a prompt to guide you in writing your Flash Fiction piece. Best of luck!

You are part of a regular diving excursion. The leader of your dive is a competent, experienced diver. She has a calming presence and you trust her capabilities.
You are under water with your group, diving in an exotic location. Your dive leader is nearby. The visibility is excellent with warm waters and unusual corals.
You look under a rock as an unusual fish caught your eye. When you look up again, you are completely alone. Your group and diving leader have disappeared.

Write a story of 1000 words about what happens next.