Funny that you call it a rough. To me it appears to be as finished as it can be. As an opening to a bigger story it does exactly what you expect: to make you curious of the rest, of what is going on. You created the right atmosphere for the hectic opening, in image and sound alike. Really like how you use the contrast of darkness and light. The transition of the brutal scenes on the surface to the almost tranquil underwater scene feels almost like a relief. Hats off to you.