The movie was a cartoon. Somehow the two main characters, which were men, came upon a new civilization. The people there crowned them kings. Then they had one last chance to leave forever, I can't remember why. But one wouldn't go. When the other got in the boat to leave, at the last second the other jumped in and went home with him. That's all I can remember.

The Road to El Dorado

Thank you so much! I have been trying to figure it out for like three years! Thankssssss :):):):)!!