The Sea Beast is on Netflix and I fully recommend giving this one a watch. It has a great piratey feel (for everyone missing Our Flat Means Death) and wonderful music. The animation just blew me away. I wish we could get more movies willing to put the work into being this gorgeous while keeping the humans (and beasts) on the clearly animated side of the uncanny valley and yet not seeming out of place.
I don't want to give too much away with the plot, but the main of it is pretty simple: child stows away on a boat that's out hunting massive ocean nightmares, and makes a few friends while causing plot and some crises of conscious.
Also, if you're looking for a way to teach someone about propaganda, this is the perfect movie.
I think, though, my favorite part is the ending song. It's a rousing sea shanty that contrasts the last act of the movie incredibly well. What do all the hymns and anthems you sing really stand for?
Mild spoiler:
You may think one of the beasts reminds you of Toothless. I did, at least, and that's how I knew it would be more important than the perfectly Kaiju-esque beast.