Filling up a boat today, I threw the Jerry can into the water.

The sound fx. for the splash is ear piercing loud. Reduce this by 5-10% for less than 5m range.
Also, I would say isn't really the correct sound expected.

Being a jerry can would be half full, there would be a lot of air buoyancy inside. So the impact shouldn't be as harsh as throwing it against rocks. While also should have the thud sound from the air inside.
I'm not explaining this very well...