Atlantis: Milo's Return (2003)

Recently, a talented researcher Milo managed to find a lost city, about which incredible legends have been going on for many centuries. Thanks to the crystal endowed with magical properties, Atlantis once again became the center of knowledge and science, having been reborn almost from oblivion. The main character not only realized his own cherished dream, but also met Queen Kidu, whom he fell in love with at first sight.

Together, they set about rebuilding the ancient city. One day, Mr. Whitmore arrives to them, who contributed to the gathering of an expedition to search for the sunken world. The man asks Milo to help in the investigation of a series of mysterious, unpleasant events taking place in the sea waters. Over the past few weeks, about ten cargo ships have sunk. Eyewitnesses claim that the incidents were caused by a giant monster. The guy can't stay away, he decides to help an old friend...