I used to watch this one cartoon film with my sister when we were little in the late 80's early 90's and we are trying to remember what it was.

This movie had a boy who went into a gottage and there was somekind of swirl hole in the floor and when he jumped there he got into another world. There was this friendly sea creature and pirates that he was hiding from and the pirates had like a treasure cave. The cartoon had very distinctive sounds and music in it. My grandmother thinks it might have been czechoslovakian make. (not sure thou).

If anyone can recocnize this I'm am so thankful! We've been trying to find this film name for years now!

Is it H R Puff n Stuff?
That one's really old! But that is the only thing that I can think of?