Great, so you can practice to get the smoothest, coolest angles! - Perhaps take some time to find fitting music, and then think of scenes that match those?
For met colours, shapes, perspective, depth, contrast made the scenes. So distractions such as fast jerky movements, loose snorkels, I would like to remove.
The backlit scubadiver that moved into one scene complemented this scene because he looked so alien and moved slow.
I hope you guys find a good camera, and if it's a gopro, learn how to use the protune. A Canon 5Dm3 with "magic lantern" shooting everything in raw allows great dynamic range fidelity and flexibility for adjustments in post.