The cartoon is about a group of talking animals that wash up on an island after a storm. It's a tropical island with a volcano and the animals aren't native to it, IIRC they were circus animals who's ship sank in the storm. By the end of the first episode the critters discover that the island floats and that the volcano isn't a normal volcano: inside the caves there is a system that controls the lava. By "powering up" the volcano they can make the island move and I think there was a way to steer it too. Or maybe the island doesn't float and moves on the sea floor somehow, but it definitely is mobile. A polar bear is elected as the island's leader. This all happens in the first 1-2 episodes.
I watched this in the mid to late 90s so it's at least that old and it's definitely a series and not a one off movie. I'm nearly certain it's Western animation not anime. I think it might have been in French originally but it was dubbed. I lived in Europe when it was aired.