Chris Hemsworth doesn't only fight injustice as an Avenger.

The "Thor: Ragnarok" star posted a photo on Instagram Thursday showing his support for the Standing Rock Sioux Tribe, which opposes the construction of an oil pipeline in North Dakota that is says will contaminate water supplies and desecrate sacred burial grounds.

RELATED: "Justice League" Cast Assembles to Oppose Dakota Access Pipeline

The photo, taken on the Australian set of "Thor: Ragnarok," Hemsworth and director Taika Waititi hold a sign that reads, "We Stand with Standing Rock." Hemsworth also took the opportunity to apologize for his "thoughtless" earlier behavior, and to call for a better understanding of issues facing First Nations people.

Standing with those who are fighting to protect their sacred land and water. #nodapl #waterislife #mniwiconi @taikawaititi I would also like to take this opportunity to raise something that has been bothering me for sometime. Last New Year's Eve I was at a "Lone Ranger" themed party where some of us, myself included, wore the traditional dress of First Nations people. I was stupidly unaware of the offence this may have caused and the sensitivity around this issue. I sincerely and unreservedly apologise to all First Nations people for this thoughtless action. I now appreciate that there is a great need for a deeper understanding of the complex and extensive issues facing indigenous communities. I hope that in highlighting my own ignorance I can help in some small way.

A photo posted by Chris Hemsworth (@chrishemsworth) on

"Last New Year's Eve I was at a 'Lone Ranger' themed party where some of us, myself included, wore the traditional dress of First Nations people," Hemsworth wrote. "I was stupidly unaware of the offence this may have caused and the sensitivity around this issue. I sincerely and unreservedly apologise to all First Nations people for this thoughtless action. I now appreciate that there is a great need for a deeper understanding of the complex and extensive issues facing indigenous communities. I hope that in highlighting my own ignorance I can help in some small way."

RELATED: Video Offers Glimpse of "Thor's" Valkyrie, Confirms "Planet Hulk" Character

Along with providing food for thought on cultural appropriation, Hemsworth's post also offers a sneak peek at Thor's costume from the upcoming Marvel Studios film. Although there's no telling whether this is the complete costume, this iteration appears to be visibly sleeker than what's been seen in previous Thor films (and sleeveless, thank Odin!).

Hemsworth's reflections mirror that of  Waititi and Australia's own fraught history with its native population. The New Zealand-born director made it a point to hire Indigenous crew members for the Marvel blockbuster. “It’s a responsibility you have to the Indigenous people," he told Buzzfeed. "You’re coming to a country and you’re bringing money into the economy and creating jobs but I think you have an even bigger responsibility to look after the people that have less opportunities."

Hemsworth isn't the first big-screen superhero to speak out against the Dakota Access Pipeline: His "Thor: Ragnarok" co-star Mark Ruffalo has been vocal about the dispute, and "Justice League" stars Ben Affleck, Gal Gadot, Jason Momoa, Ezra Miller and Ray Fisher posted a video last month in support of the protesters.

Opening Nov. 3, 2017, "Thor: Ragnarok" also stars Tom Hiddleston, Idris Elba, Anthony Hopkins, Cate Blanchett, Tessa Thompson, Jeff Goldblum, Karl Urban and Mark Ruffalo.