1 of 6
2 of 6
3 of 6
Watts chats on the phone on a boat in Croatia in a pale blue Melissa Odabash one-piece bathing suit, as Di did aboard boyfriend Dodi al-Fayed's yacht during a much-photographed Mediterranean cruise in the summer of 1997.
4 of 6
Watts wears the beaded silk georgette Jacques Azagury gown Princess Di showed off at her final official engagement – the English National Ballet's June 1997 performance of Swan Lake in London. Watts admitted she was "terrified" to play such a beloved figure from recent history: "It's very scary, and I kind of wanted to say no," she said. "But now I'm doing all the research … I just hope we make a good film and people can learn something new about her that's interesting."
5 of 6
LADY IN BLACK
Watts wears an outfit similar to the one Princess Di wore to Angola in January 1997 to visit Red Cross projects. Watts said it's a task to find the real Diana: "There are a lot of people that knew her, and a lot of books to read and so much information, and one story is different to the next, so it's hard to gauge what was the truth," she said. "It's going to be a tough one, it's a big beast to take on, I just try to do my best."
6 of 6
Watts playfully cavorts with Cas Anvar, the actor portraying al-Fayed, as they recreate a romantic moment – interrupted by cameras – aboard the Egyptian playboy's luxury yacht in the summer of 1997, just weeks before their death in Paris. "It is such an honor to be able to play this iconic role – Princess Diana was loved across the world and I look forward to rising to the challenge of playing her on screen," Watts said.
Ellen and Portia Have a PDA-filled Day, Plus Gwyneth Paltrow, Keke Palmer, John Stamos & More
10 Seriously A-list Selfies We Wish We'd Photobombed
Star Tracks: Celebs on Social