Is there any animated movie or cartoon that you kind of remember from when you when a kid but can't name or even recall that clearly?

When I was a kid I remember watching all the time an animated fantasy movie. I think that the plot was that a princess was kidnapped by goblins and taken to their underground kingdom, so a hero had to descend to the pits to save her.
I don't remember much about it; the boy at one point had to use a string to not get lost in the caverns, but it ran out. That's the only scene I remember, that and the goblins storming the castle. Does this sound familiar to anyone?