Margot Robbie Soaks Up Sun in Bikini, Wears 'Mama' Necklace on Vacation

Margot Robbie is enjoying some much-needed R&R after becoming a new mother ... lighting up the beach in a tight gray bikini just months after giving birth.

The actress was down in her native Australia enjoying Easter weekend on the Gold Coast ... and, the weather in the area looks beautiful -- which got MR to strip down to a bikini for a dip in the ocean.

Check out the pics ... Margot's wearing a two-piece with a bit more coverage than some skimpy ensembles we've seen celebs wear, chatting with a pal while enjoying the afternoon sun.

While there's not a glimpse of her kiddo in the pics, Margot's clearly embracing her new role as "mama" ... 'cause the word is written on the gold necklace wrapped around her neck.

She also shared a sweet moment with her producer husband Tom Ackerley ... with her man wrapping his hands around her waist in a sweet embrace while laid out on a lounge chair.

The two new parents welcomed their first child together in the fall ... a few months after Robbie revealed she had a baby bump while stepping out on vacay.

While she hasn't talked publicly about being a mom yet, reports have said she's loving the experience ... spending a ton of time in L.A. with a little baby boy, according to People.