Women in their mid-40's ought to be either really grateful to — or jealous of — Naomi Watts, 43, and Robin Wright, 45. The two lovely ladies don't look a day over 25 in their swimwear, proving that age is just a number.

The two women stripped down on a beach in Sydney, Australia, on Thursday, while filming The Grandmothers. Directed by Anna Fontaine (Coco Before Chanel), the film features Watts and Wright as lifelong friends who fall for each other's sons, played by Xavier Samuel (The Twilight Saga) and James Frecheville (Animal Kingdom), according to the Daily Mail.

Watts has been working hard, despite also being a wife to Liev Schreiber and a mother to their two sons, Sasha, 4, and Sammy, 3. She will play Princess Diana in Caught in Flight, a film described as "a compelling portrait of Diana, Princess of Wales during the last two years of her life," according to BBC News. The focus will be on former Princess of Wales' relationship with doctor Hasnat Kahn.

"[It is] such an honour to be able to play this iconic role," Watts said.

Read our recent interview with Wright here.

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