One of his biggest challenges while shooting Aquaman initially was to build an underwater kingdom-a world scarcely featured on the silver screen. But what was at first an obstacle soon became an opportunity as it gave Wan and the design team lots of creative freedom.

This is evident in the recently released trailers that show spectacular creatures, ranging from giant sea horses and fierce sharks to black manta rays, gigantic crabs and huge turtles.

"This is a movie that we would not have been able to make five years ago," Wan says. "But now, we used this technique called 'dry-for-wet', which is to film the actors in a blue-screen environment after putting them in contraptions to simulate floating underwater."

Heard, who plays Mera, says she trained six days a week for more than four months. She was clad in a skin-tight suit and had to act on an empty film set that looked like an airline hangar.

Meanwhile, as fans await the breathtaking underwater duels, there's another "battle" looming off-screen.

Over the past decade, Marvel superheroes have grossed nearly 13 billion yuan ($1.9 billion), and Venom is now ruling in domestic theaters.

So, will the comparatively lackluster DC superheroes now overcome their powerful rivals in China?

It's a question for superheroes to answer.

Contact the writer at xufan@chinadaily.com.cn