Cool game. Game is super smooth and fun. :)
One feedback idea: Instead of numbers, the required speed could be shown visually next to the speedometer.
The shipwreck was visually beautiful! Gaining speed with the harpoon was fun. The goal of the game was a little bit of a mystery. When I reached the sinking ship the game restarted, maybe a "level passed" text or something similar would be good. I could not hear diver's breathing, so it was difficult to know how much oxygen i had.
Very atmospheric game! I loved the visuals and music! I had a hard time to play this on my pc because loading time was long and couple of times i got a error message (WebGL context lost, please reload the page). But when i got the game it was lovely! Maybe the first level could have hover text explaining what every tool does?