This is just practice. Nothing to be stressed about. Practice is good.
What if the sharks are attacking all over the world. There are eco-terrorist strikes against the shark fin boats, and the commercial tuna fishing boats. Think Monkey Wrench Gang, but on the oceans. Perhaps Green Peace is blamed for some of the attacks.
Professor Katz and his students, Summer and Chas, are out investigating why sharks are attacking. This means that they are observing, counting sharks, and maybe catching sharks to take blood samples to see if something chemical has changed. Summer has her scuba certification, but she hasn’t been on an open ocean dive since she before she was bitten. She is in her mid-twenties, and was bitten while riding a surf board at 16 – so about ten years. Chas has no problem and loves to scuba dive. So it is usually Chas and Professor Katz in the water or cage, depending. Chas is filming, and Summer is recording data. Captain Mike and First Mate (who still needs a name) are get rich quick guys and go way back with Professor Katz (who has been known to get on Shark Week for his staged shark antics). Bruno is a crew member, there to do heavy lifting, and to keep an eye on the research that is being done. He is also searching for the item, and thinks that Captain Mike might have it (and he does). He has a beef with Prof. Katz for a previous shark stunt which caused harm to the shark. Bruno is an eco-terrorist shark man.
Story Engineering has a checklist at Writers that is everything that one should have ready and know when one is writing a story. I am almost through the Story Engineering book, and I’m going to have to read it again because a lot of it just didn’t stick. But that’s okay. Because this is just practice.

Conceptual hook: Shark eco-terrorists striking back at mankind’s harmful use of the ocean. Sharks that change into humans.
Theme: Seize the day before the day seizes you (Summer’s moto), Kill or be killed (Bruno’s motto), Anything for a buck (Captain Mike’s motto), Anything for fame (Prof. Katz’s motto). I suspect the theme might be morphing into something similar to “respect the oceans.” Of course, I wasn’t clear on the theme from before.
Opening: Stuff that happens before the 1st plot point, where the story really starts.
First plot point
Mid-point contextual shift
dark moment or lull right before second plot point
Second plot point (hero becomes a hero)
Ending that ties up all of the strings

It’s practice. Don’t panic