To clarify some controls I forgot to add in the controls menu:

Use the mouse wheel to change between the knife and speargun (after unlocking the speargun) 

Hold Shift to swim faster but consume stamina.

Also there is a bug in the game where some times when choosing an option after completing a wave, the other option will get applied. I am sorry I didn't catch it in time. 

Some little bubbles when moving would sell the underwater environment a bit better but still, fun wave survival game.