Livvy Dunne Flashes Butt at Beach After Getting 'Baywatch' Role

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.

Dunne captioned the post, "I’m not a lifeguard, but i play one on tv" ... and we'd still want her to save us any day of the week!

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.