This December, James Wan's Aquaman is set to deliver a live-action blockbuster experience unlike anything we've ever seen. Sure, we've seen plenty of big movies set out on the ocean, but the upcoming DC blockbuster is different because most of the action will be set under the water. Because the idea is so different, the production had to do a lot of tests to make sure that everything looked right -- and according to Wan, there were a few significant surprises in store for them that they weren't expecting:

So even though we did a lot of dry-for-wet, we wanted to make sure things looked somewhat authentic underwater. We would get costumes, sets and our actors and submerge them underwater. We did so much study just to see what they would look like and the most surprising thing that we discovered early on is people, objects and stuff do not look wet under water. It only looks wet when you take it out of water. When it's glistening and it's dripping wet, that's how something looks wet. But when you're underwater it actually looks matte. That concept was a bit tricky to wrap our heads around.

It's true that Aquaman didn't do a ton of underwater shooting, instead opting to mostly use a combination of wirework and visual effects, but there was still plenty of work that needed to be done with the wet stuff to make sure that the blockbuster looks realistic. And while obviously stuff like hair looks different when submerged, the same isn't really true for skin and other surfaces. Sure, you'll see water droplets when things come out of the water, but it didn't really occur to James Wan until the testing that "wet" isn't really a factor before that.

James Wan talked about this discovery late last month in the edit bay for Aquaman on the Warner Bros. lot in Burbank, California -- which I had the chance to visit along with a small group of other journalists. One thing he also added, though, is that the discovery of how things look underwater presented its own issues. Specifically, people may not sweat when they are beneath the waves, but they do when they are on a movie set and surrounded by lights while performing action sequences. Wan explained,

We constantly had to go in there and pat our actors down with makeup because under those bright lights and all the stunts they were constantly sweating and all that. You don't see water underwater. You don't see sweat... We want to shoot as much [as we can practically]. Even if visual effects was to come in and augment a lot of it, they want to start with something that is real, that is tangible.

It should ultimately make for a whole new cinematic experience, and fans will get to have it when Aquaman -- starring Jason Momoa, Amber Heard, Patrick Wilson, and more -- arrives in theaters on December 21st.