“In a cumulative sense, every scene leading up to the conclusion of this season was quite challenging. We took several weeks to shoot them. The scenes where the two characters are being actively chased by the paparazzi were, in my opinion, quite difficult to film. Debicki, 33, exclusively tells PEOPLE that it’s highly physical. “After a few weeks of that, we were exhausted and completely depleted. We thought it was similar to performing a stunt in that there wasn’t much acting involved and more of a physical experience taking place.

“The feeling was almost like being underwater. You’re just kind in this swamp of noise, of harassment, of being pursued,” she says. “As the actor playing the role, the character is just constantly focusing on where they’re trying to get to, but there’s just this accumulation of obstacles in the way of that, and that was a very kind of difficult, taxing thing to experience.”

On Aug. 31, 1997, the Princess of Wales and the Harrods heir were traveling by car in Paris with a driver and bodyguard pursued by paparazzi when their vehicle slammed into a support column of the Pont de l’Alma tunnel, flipped and came to a rest in front of oncoming traffic. Dodi and the driver died instantly while Diana died later in the hospital. She was 36 years old

In order to depict the royal family ageing over the years, The Crown’s cast rotated every two seasons. Debicki replaced Emma Corrin as Princess Diana in seasons five and six. The actor claims that presenting a different side of Diana changed over the last season

“I felt like I really had an opportunity in this season to just really focus on the relationship between Diana and her boys. Just that love, the joy, and the relief of spending time with them, and feeling really truly yourself when you have your children with you, and a real sense of kind of purpose,” Debicki tells PEOPLE. “That was so important for me because obviously we know where the story is heading. I really focused, whenever there was an opportunity, to show how incredibly alive and beautiful this person was.”

Netflix is currently airing Part 1 of The Crown season 6.