How would your character react....

Watching this video and listening to the calm breathing of the cameraman, I was prompted to wonder about reactions to situations.
What seems incredible and extremely dangerous to me, obviously isn't an adrenaline pumping event to the diver or the sharks.
So, writing a character's reactions must depend on their level of knowledge, experience, courage, bravado and common sense.
Like driving.. it's dangerous. Just reading the statistics proves that. Does it take courage to get behind the wheel? Perhaps.. but we have experience.. We (hopefully) treat our driving with respect and extreme care. Don't we? Not bravado...
Diving is a dangerous sport. Sharks CAN be dangerous. So we immediately associate their presence with an element of fear. (at least I do)
These sharks change my perception. They obviously aren't dangerous.
The Grey Nurse shark is badly maligned if it is given  a fear factor. These creatures prove how little they want to maul or attack a human.
Even knowing they are minding their own business... my adrenaline would be pumping.
Swimming, snorkelling among large fish, kingfish on Lord Howe Island... made me nervous..
Anyhow.. this isn't about me.. I am just re assessing the ideas of reactions.
What we count as courage, could just be confidence in collected knowledge. But does that take anything away from our character? To be experienced and to get to this level of expertise has taken courage?
Ok.. just thinking aloud as I count how many sharks are swimming within range of the lens.