Atlantis: The Lost Empire (2001)

A young adventurer who doesn't have any experiences at all becomes the key to untangling a mystery from the past when he decides to join a team of daredevil explorers in an attempt to search for the missing empire of Atlantis. A naive yet more than determined museum cartographer Milo Thatch aspires to finish the quest that was started by his late grandfather, who used to be a famous explorer.