Olivia Dunne is getting used to sandy beaches and how her impressive backside looks in lifeguard red … flaunting her booty while celebrating her new “Baywatch” role!

The former gymnast and influencer celebrated her new gig with a couple of Instagram pics capturing her excited face and the script for the show … with its large red emblem embossed on the cover.

While Livvy’s grin is front and center in one pics, fans eyes were probably pulled a little lower by another … which prominently featured her sculpted legs and bottom.

While this is Olivia’s first time addressing the casting, we already told you this was going down … relaying that sources revealed to us she will play Grace in the Shay Mitchell, Brooks Nader-led show.

The cast had its first table-read last week … and the show is scheduled to hit Fox later on in the year.