Need we say more??

The 2020 SI Swim cover model and her friends took a trip down to Mexico this week for a getaway in paradise ... and OC and DW made sure to bring their best 2-pieces!!

The squad has been living it up the past few days -- from dinners to expensive boat rides to dancing to Cardi B and Meg Thee Stallion's "WAP" -- with everyone looking equally happy and sexy the whole time.

OC's 23-year-old sister, Sophia, was also along for the ride ... and if you haven't been introduced to her in the past -- it's our pleasure to do the honor.

It goes without saying Olivia's boo, Carolina Panthers superstar Christian McCaffrey, ain't along for the trip -- he's currently fighting to get back on the field after suffering a high ankle sprain earlier in the season.

Of course, it's Halloween ... and we tried like hell to come up with a punny theme to go along with the holiday ... but can't think of anything.