You've had some fabulous feedback, Yvonne. Opening straightaway with the shark attack is a great idea and pulls the reader/agent in.
I was a little surprised towards the end of the synopsis to hear that Josh cared about green issues. I don't know how this evolves in your novel but I would expect that to come in somewhere earlier in the synopsis. Does he care about the ocean because of his love of surfing? The link if there was one was unclear for me. Just my two pennies worth. Good luck and congratulations with having finished the novel and getting ready to pitch to agents 👍