Some new footage of DreamWorks Animation's upcoming How to Train Your Dragon: The Hidden World was revealed on Saturday by writer-director Dean DeBlois at the Toronto International Film Festival.

In the final chapter of DeBlois' emotional trilogy, the Viking island of Berk that protagonist Hiccup (voiced by Jay Baruchel) now rules has changed since 2014's How to Train Your Dragon 2. It's now overcrowded with humans and dragons who live side by side.

In the first new clip, as Hiccup ponders the situation, there’s a flashback of a wide-eyed young Hiccup in his father’s arms, as his late father, Stoick, described a legend identifying a hidden world where dragons reside, across the sea.

Back in the present day, Hiccup shares this story with his girlfriend Astrid (America Ferrera) as they discuss the next step in their relationship. “This brings Stoick back and gives him a warm presence in the film,” said DeBlois, adding, “In the old world, finding the Hidden World could have been a means to ends war between humans and dragons. But in the new world, finding it may be an answer to preserving the peace for people and dragons [who together face a new threat]."

Another newly unveiled clip gave attendees a first look at the Hidden World, which DeBlois described as a “system of vast chambers and corridors that run beneath the ocean and continent.

"The look is ethereal," he said. "We wanted something that transcended the idea of a cave. Part of that was delving into bioluminescence and was of channeling light into this subterranean space with the use of crystals that could carry light from magma. We wanted it to be an exotic world that still feels like it belongs here on Earth. But it's still a place for dragons and not for humans."

In the clip, the dragon Toothless is in the Hidden World with his love interest, a Light Fury (whom Toothless gets acquainted with in another clip, dubbed "First Date," which was also screened), but when he doesn't come home to Berk, Hiccup and Astrid set off to find him.

DeBlois related that when the couple discover the Hidden World and Toothless becoming the alpha dragon among his peers, "Hiccup is heartbroken seeing Toothless in the place where he thrives and belongs. It's difficult for him to process."

But soon Toothless has to rescue Hiccup and Astrid when they inadvertently cause a commotion.

Based on Cressida Cowell's book series, the film trilogy began with 2010's How to Train Your Dragon, which DeBlois co-directed with Chris Sanders. It and its 2014 sequel, written and directed by DeBlois, were Oscar-nominated.

How to Train Your Dragon: The Hidden World is scheduled to open March 1.