The Brit starred in director Guillermo Del Toro's 2013 movie and was on board for the filmmaker's follow-up, but when the movie studio exchanged hands and Del Toro stepped away from the project, Hunnam had second thoughts.
And when the new filmmakers wanted to turn the film around in a hurry, Charlie's schedule didn't quite fit and he was forced to turn down the sequel.
"By the time they circled around and decided that they were gonna make it with a different director, we had a conversation about it but I was booked up," the "King Arthur: Legend of the Sword" actor tells Collider. "There were business elements of it that required them to go into production very quickly."
"Legendary had just been acquired by Wanda out of China, and they wanted that film made very quickly and I wasn't available. That's just what happens."
"I didn't deeply lament it... We'd already done one Pacific Rim, so I felt like, 'Go with God. Go do your thing'. I actually haven’t seen the sequel, so I didn't ever give myself an opportunity to really think about whether I regret that decision or not."
Written by Travis Beacham and del Toro, "Pacific Rim" is set in the future, when Earth is at war with colossal sea monsters called Kaiju which have emerged from an interdimensional portal on the bottom of the Pacific Ocean. The follow-up, 2018's "Pacific Rim: Uprising", was directed by Steven S. DeKnight and starred John Boyega and Scott Eastwood.