Looking for an 80's cartoon about a boy trying to avenge his father's death by killing the shark and retrieving the knife that his dad left in the shark.

There is a story called “Ghost of the Lagoon” apparently about a boy named Mako who wants to kill a shark named Tupa for revenge- this may be the subject of the cartoon. There’s a YouTube video if you Google this, but I can’t see the videos at work, so don’t know if it’s what you are looking for.

Reminds me of the awesome YA novel “Call it Courage”. Off-topic.

wow, it sounds very interesting

I wish the OP would return and tell us if either of these answers are correct!

I know mine isn’t correct.