First of all the game seems well polished. The audio and selfmade art fits perfectly to the feel of the scene and the dangers get more difficult over time + you have a "side objective" with the crates.
Sometimes it is hard to tell whether a boat gets "wrecked" or dodges an obstacle. I would like to see an indicator, so I know "eh, the captain knows. the light source is enough!"
There is not a lot left to discover after the first or second attempt. Maybe new boat/ stone types and an increasing map size could work.
You did a great job. Especially given the short timeframe to plan everything out. The game felt pretty well designed.